UIPanGestureRecognizer - 仅垂直或水平

Question

我有一个视图，它有一个 UIPanGestureRecognizer 来垂直拖动视图。所以在识别器回调中，我只更新 y 坐标来移动它。这个视图的父视图，有一个UIPanGestureRecognizer，它将水平拖动视图，只是更新x坐标。

问题是第一个UIPanGestureRecognizer正在接受事件来垂直移动视图，所以我不能使用superview手势。

我试过了

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
 shouldRecognizeSimultaneouslyWithGestureRecognizer:
                            (UIGestureRecognizer *)otherGestureRecognizer;

两者都可以，但我不希望这样。我希望只有在运动明显水平时才能检测到水平方向。因此，如果UIPanGestureRecognizer 具有方向属性，那就太好了。

我怎样才能实现这种行为？我发现文档非常混乱，所以也许有人可以在这里更好地解释一下。

Answer 1

只需为垂直平移手势识别器执行此操作，它对我有用：

- (BOOL)gestureRecognizerShouldBegin:(UIPanGestureRecognizer *)panGestureRecognizer {
    CGPoint velocity = [panGestureRecognizer velocityInView:someView];
    return fabs(velocity.y) > fabs(velocity.x);
}

对于 Swift：

func gestureRecognizerShouldBegin(_ gestureRecognizer: UIPanGestureRecognizer) -> Bool {
    let velocity = gestureRecognizer.velocity(in: someView)
    return abs(velocity.x) > abs(velocity.y)
}

Answer 2

我在@LocoMike 提供的答案中创建了一个带有子类化的解决方案，但是通过@Hejazi 提供的初始速度使用了更有效的检测机制。我也在使用 Swift，但如果需要，这应该很容易转换为 Obj-C。

相对于其他解决方案的优势：

• 比其他子类化解决方案更简单、更简洁。无需管理其他状态。
• 方向检测发生在发送 Began 操作之前，因此如果滑动错误的方向，您的平移手势选择器不会收到任何消息。
• 确定初始方向后，不再参考方向逻辑。这会导致在初始方向正确时激活识别器的一般期望行为，但如果用户的手指没有沿着该方向完美移动，则不会在开始后取消手势。

代码如下：

import UIKit.UIGestureRecognizerSubclass

enum PanDirection {
    case vertical
    case horizontal
}

class PanDirectionGestureRecognizer: UIPanGestureRecognizer {

    let direction: PanDirection

    init(direction: PanDirection, target: AnyObject, action: Selector) {
        self.direction = direction
        super.init(target: target, action: action)
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesMoved(touches, with: event)

        if state == .began {
            let vel = velocity(in: view)
            switch direction {
            case .horizontal where fabs(vel.y) > fabs(vel.x):
                state = .cancelled
            case .vertical where fabs(vel.x) > fabs(vel.y):
                state = .cancelled
            default:
                break
            }
        }
    }
}

使用示例：

let panGestureRecognizer = PanDirectionGestureRecognizer(direction: .horizontal, target: self, action: #selector(handlePanGesture(_:)))
panGestureRecognizer.cancelsTouchesInView = false
self.view.addGestureRecognizer(panGestureRecognizer)

func handlePanGesture(_ pan: UIPanGestureRecognizer) {
    let percent = max(pan.translation(in: view).x, 0) / view.frame.width

    switch pan.state {
    case .began:
    ...
}

Answer 3

我发现它创建了一个 UIPanGestureRecognizer 的子类

DirectionPanGestureRecognizer：

#import <Foundation/Foundation.h>
#import <UIKit/UIGestureRecognizerSubclass.h>

typedef enum {
    DirectionPangestureRecognizerVertical,
    DirectionPanGestureRecognizerHorizontal
} DirectionPangestureRecognizerDirection;

@interface DirectionPanGestureRecognizer : UIPanGestureRecognizer {
    BOOL _drag;
    int _moveX;
    int _moveY;
    DirectionPangestureRecognizerDirection _direction;
}

@property (nonatomic, assign) DirectionPangestureRecognizerDirection direction;

@end

DirectionPanGestureRecognizer.m：

#import "DirectionPanGestureRecognizer.h"

int const static kDirectionPanThreshold = 5;

@implementation DirectionPanGestureRecognizer

@synthesize direction = _direction;

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    [super touchesMoved:touches withEvent:event];
    if (self.state == UIGestureRecognizerStateFailed) return;
    CGPoint nowPoint = [[touches anyObject] locationInView:self.view];
    CGPoint prevPoint = [[touches anyObject] previousLocationInView:self.view];
    _moveX += prevPoint.x - nowPoint.x;
    _moveY += prevPoint.y - nowPoint.y;
    if (!_drag) {
        if (abs(_moveX) > kDirectionPanThreshold) {
            if (_direction == DirectionPangestureRecognizerVertical) {
                self.state = UIGestureRecognizerStateFailed;
            }else {
                _drag = YES;
            }
        }else if (abs(_moveY) > kDirectionPanThreshold) {
            if (_direction == DirectionPanGestureRecognizerHorizontal) {
                self.state = UIGestureRecognizerStateFailed;
            }else {
                _drag = YES;
            }
        }
    }
}

- (void)reset {
    [super reset];
    _drag = NO;
    _moveX = 0;
    _moveY = 0;
}

@end

这只会在用户开始拖动所选行为时触发手势。将方向属性设置为正确的值，一切就绪。

Answer 4

我尝试使用 UIPanGestureRecognizer 水平限制有效区域。

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
    if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {

        UIPanGestureRecognizer *panGesture = (UIPanGestureRecognizer *)gestureRecognizer;
        CGPoint velocity = [panGesture velocityInView:panGesture.view];

        double radian = atan(velocity.y/velocity.x);
        double degree = radian * 180 / M_PI;

        double thresholdAngle = 20.0;
        if (fabs(degree) > thresholdAngle) {
            return NO;
        }
    }
    return YES;
}

那么，只有在 thresholdAngle 度范围内水平滑动才能触发此平移手势。

Answer 5

Swift 3.0 答案：只处理垂直手势

    override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
    if let pan = gestureRecognizer as? UIPanGestureRecognizer {
        let velocity = pan.velocity(in: self)
        return fabs(velocity.y) > fabs(velocity.x)
    }
    return true

}

Answer 6

以下解决方案解决了我的问题：

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    if ([gestureRecognizer.view isEqual:self.view] && [otherGestureRecognizer.view isEqual:self.tableView]) {
        return NO;
    }
    return YES;
}

这实际上只是检查 pan 是在主视图还是 tableView 上。

Answer 7

Swift 3 版本的 Lee 对懒人的回答

import UIKit
import UIKit.UIGestureRecognizerSubclass

enum PanDirection {
    case vertical
    case horizontal
}

class UIPanDirectionGestureRecognizer: UIPanGestureRecognizer {

    let direction : PanDirection

    init(direction: PanDirection, target: AnyObject, action: Selector) {
        self.direction = direction
        super.init(target: target, action: action)
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesMoved(touches, with: event)

        if state == .began {

            let vel = velocity(in: self.view!)
            switch direction {
            case .horizontal where fabs(vel.y) > fabs(vel.x):
                state = .cancelled
            case .vertical where fabs(vel.x) > fabs(vel.y):
                state = .cancelled
            default:
                break
            }
        }
    }
}

Answer 8

我采用了Lee Goodrich 的answer 并扩展了它，因为我特别需要一个单向平移。像这样使用它：let pan = PanDirectionGestureRecognizer(direction: .vertical(.up), target: self, action: #selector(handleCellPan(_:)))

我还添加了一些评论，以便更清楚地了解实际做出的决定。

import UIKit.UIGestureRecognizerSubclass

enum PanVerticalDirection {
    case either
    case up
    case down
}

enum PanHorizontalDirection {
    case either
    case left
    case right
}

enum PanDirection {
    case vertical(PanVerticalDirection)
    case horizontal(PanHorizontalDirection)
}

class PanDirectionGestureRecognizer: UIPanGestureRecognizer {

    let direction: PanDirection

    init(direction: PanDirection, target: AnyObject, action: Selector) {
        self.direction = direction
        super.init(target: target, action: action)
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesMoved(touches, with: event)

        if state == .began {
            let vel = velocity(in: view)
            switch direction {

            // expecting horizontal but moving vertical, cancel
            case .horizontal(_) where fabs(vel.y) > fabs(vel.x):
                state = .cancelled

            // expecting vertical but moving horizontal, cancel
            case .vertical(_) where fabs(vel.x) > fabs(vel.y):
                state = .cancelled

            // expecting horizontal and moving horizontal
            case .horizontal(let hDirection):
                switch hDirection {

                    // expecting left but moving right, cancel
                    case .left where vel.x > 0: state = .cancelled

                    // expecting right but moving left, cancel
                    case .right where vel.x < 0: state = .cancelled
                    default: break
                }

            // expecting vertical and moving vertical
            case .vertical(let vDirection):
                switch vDirection {
                    // expecting up but moving down, cancel
                    case .up where vel.y > 0: state = .cancelled

                    // expecting down but moving up, cancel
                    case .down where vel.y < 0: state = .cancelled
                    default: break
                }
            }
        }
    }
}

Answer 9

斯威夫特 4.2

解决方案仅支持垂直平移手势，与水平相同。

let pan = UIPanGestureRecognizer(target: self, action: #selector(test1))
pan.cancelsTouchesInView = false
panView.addGestureRecognizer(pan)

解决方案 1：

@objc func panAction(pan: UIPanGestureRecognizer) {

        let velocity = pan.velocity(in: panView)
        guard abs(velocity.y) > abs(velocity.x) else {
            return
        }
}

解决方案 2：

  [UISwipeGestureRecognizer.Direction.left, .right].forEach { direction in
        let swipe = UISwipeGestureRecognizer(target: self, action: #selector(swipeAction))
        swipe.direction = direction
        panView.addGestureRecognizer(swipe)
        pan.require(toFail: swipe)
    }

然后滑动手势将吞噬平移手势。当然，你不需要在swipeAction做任何事情。

Answer 10

这是 Swift 5

中的自定义平移手势

U可以限制它的方向和方向的最大角度，也可以限制它的方向的最小速度。

enum PanDirection {
    case vertical
    case horizontal
}

struct Constaint {
    let maxAngle: Double
    let minSpeed: CGFloat

    static let `default` = Constaint(maxAngle: 50, minSpeed: 50)
}


class PanDirectionGestureRecognizer: UIPanGestureRecognizer {

    let direction: PanDirection

    let constraint: Constaint


    init(direction orientation: PanDirection, target: AnyObject, action: Selector, constraint limits: Constaint = Constaint.default) {
        direction = orientation
        constraint = limits
        super.init(target: target, action: action)
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesMoved(touches, with: event)
        let tangent = tan(constraint.maxAngle * Double.pi / 180)
        if state == .began {
            let vel = velocity(in: view)
            switch direction {
            case .horizontal where abs(vel.y)/abs(vel.x) > CGFloat(tangent) || abs(vel.x) < constraint.minSpeed:
                state = .cancelled
            case .vertical where abs(vel.x)/abs(vel.y) > CGFloat(tangent) || abs(vel.y) < constraint.minSpeed:
                state = .cancelled
            default:
                break
            }
        }
    }
}

这样调用：

    let pan = PanDirectionGestureRecognizer(direction: .vertical, target: self, action: #selector(self.push(_:)))
    view.addGestureRecognizer(pan)

    @objc func push(_ gesture: UIPanGestureRecognizer){
        if gesture.state == .began{
            // command for once
        }
    }

或

    let pan = PanDirectionGestureRecognizer(direction: .horizontal, target: self, action: #selector(self.push(_:)), constraint: Constaint(maxAngle: 5, minSpeed: 80))
    view.addGestureRecognizer(pan)

Answer 11

您可以在UIView 到UIPanGestureRecognizer 上找到拖动方向。请按照代码进行操作。

 - (void)viewDidLoad {
    [super viewDidLoad];
    flipFoward = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(doFlipForward:)];
    [flipFoward setMaximumNumberOfTouches:1];
    [flipFoward setMinimumNumberOfTouches:1];
    [flipFoward setDelegate:self];
    [self.view addGestureRecognizer:flipFoward];
    flipBack = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(doFlipBack:)];
    [flipBack setMaximumNumberOfTouches:1];
    [flipBack setMinimumNumberOfTouches:1];
    [flipBack setDelegate:self];
    [self.view addGestureRecognizer:flipBack];
}

#pragma mark -
#pragma mark RESPONDER

-(void)doFlipForward:(UIGestureRecognizer *)aGestureRecognizer{
    NSLog(@"doFlipForward");
    if([(UIPanGestureRecognizer*)aGestureRecognizer state] == UIGestureRecognizerStateBegan) {
        NSLog(@"UIGestureRecognizerStateBegan");
    }
    if([(UIPanGestureRecognizer*)aGestureRecognizer state] == UIGestureRecognizerStateChanged) {
        NSLog(@"UIGestureRecognizerStateChanged");
    }
    if([(UIPanGestureRecognizer*)aGestureRecognizer state] == UIGestureRecognizerStateEnded) {
        NSLog(@"UIGestureRecognizerStateEnded");
    }
}

-(void)doFlipBack:(UIGestureRecognizer *)aGestureRecognizer{
    NSLog(@"doFlipBack");
    if([(UIPanGestureRecognizer*)aGestureRecognizer state] == UIGestureRecognizerStateBegan) {
        NSLog(@"UIGestureRecognizerStateBegan1");
    }
    if([(UIPanGestureRecognizer*)aGestureRecognizer state] == UIGestureRecognizerStateChanged) {
        NSLog(@"UIGestureRecognizerStateChanged1");
    }
    if([(UIPanGestureRecognizer*)aGestureRecognizer state] == UIGestureRecognizerStateEnded) {
        NSLog(@"UIGestureRecognizerStateEnded1");
    }
}

#pragma mark -
#pragma mark DELEGATE

-(BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{
    CGSize size = [self.view bounds].size;
    CGFloat touchX = [gestureRecognizer locationInView:self.view].x;
    if((gestureRecognizer == flipFoward) 
       && touchX >= (size.width - 88.0f))
    {
        return YES;
    }
    if((gestureRecognizer == flipBack)
       && touchX <= 88.0f)
    {
        return YES;
    }
    return NO;
}

Answer 12

这是我的解决方法：

首先我启用了同时泛手势识别。

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {

return YES;

然后我隔离水平和垂直平移手势（累加器是 NSMutableArray 属性）：

- (void)verticalPan :(UIPanGestureRecognizer *) sender {

CGPoint touch  = [sender translationInView:self];
NSValue *value = [NSValue valueWithCGPoint:touch];
[accumulator addObject:value];

int firstXObjectValue = (int)[[accumulator objectAtIndex:0] CGPointValue].x ;
int lastXObjectValue =  (int)[[accumulator lastObject] CGPointValue].x;

int firstYObjectValue = (int)[[accumulator objectAtIndex:0] CGPointValue].y;
int lastYObjectValue =  (int)[[accumulator lastObject] CGPointValue].y;

if (abs(lastYObjectValue - firstYObjectValue) < 4 && abs(lastXObjectValue - firstXObjectValue) > 4) {
    NSLog(@"Horizontal Pan");

    //do something here
}
else if (abs(lastYObjectValue - firstYObjectValue) > 4 && abs(lastXObjectValue - firstXObjectValue) < 4){
    NSLog(@"Vertical Pan");

    //do something here
}

if (accumulator.count > 3)
    [accumulator removeAllObjects];

我在这里推了一个例子：

add custom pan in scrollview

Answer 13

let pangesture = UIPanGestureRecognizer(target: self, action: "dragview:")
yourview.addGestureRecognizer(pangesture)


func dragview(panGestureRecognizer:UIPanGestureRecognizer)
{
    let touchlocation = panGestureRecognizer.locationInView(parentview)
    yourview.center.y = touchlocation.y //x for horizontal 
}

Answer 14

您可以使用简单的panGestureRecognizer。无需使用 pandirectionregognizer 或其他东西。只需使用 translationInview 的 y 值 下面的代码只上下移动拖动视图

- (void)gesturePan_Handle:(UIPanGestureRecognizer *)gesture {
    if (gesture.state == UIGestureRecognizerStateChanged) {
        CGPoint translation = [gesture translationInView:gesture.view];
        recognizer.view.center = CGPointMake(recognizer.view.center.x, recognizer.view.center.y + translation.y);
        [gesture setTranslation:CGPointMake(0, 0) inView:gesture.view];
    }
}

Answer 15

- (void)dragAction:(UIPanGestureRecognizer *)gesture{
      UILabel *label = (UILabel *)gesture.view;
      CGPoint translation = [gesture translationInView:label];
     label.center = CGPointMake(label.center.x + translation.x,
                             label.center.y + 0);
    [gesture setTranslation:CGPointZero inView:label];}

我为只需要水平滚动的对象创建了 PanGestureRecognizer @selector 操作方法。

 UIPanGestureRecognizer *gesture = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(smileyDragged:)];
    [buttonObject addGestureRecognizer:gesture];

Answer 16

快捷方式

override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
    if let panGestureRecognizer = gestureRecognizer as? UIPanGestureRecognizer {
        return isVerticalGesture(panGestureRecognizer)
    }
    return false
}

private func isVerticalGesture(_ recognizer: UIPanGestureRecognizer) -> Bool {
    let translation = recognizer.translation(in: superview!)
    if fabs(translation.y) > fabs(translation.x) {
        return true
    }
    return false
}

Answer 17

对于所有 Swift 用户来说，这将完成这项工作 :)

import Foundation
import UIKit.UIGestureRecognizerSubclass


class DirectionPanGestureRecognizer: UIPanGestureRecognizer {

let kDirectionPanThreshold = CGFloat(5)
var drag = true
var moveX = CGFloat(0)
var moveY = CGFloat(0)

override init(target: AnyObject, action: Selector) {
    super.init(target: target, action: action)
}

override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {
    super.touchesMoved(touches, withEvent: event)
    if state == .Failed {
        return
    }

    let nowPoint = touches.anyObject()?.locationInView(view)
    let prevPoint = touches.anyObject()?.previousLocationInView(view)
    moveX += prevPoint!.x - nowPoint!.x
    moveY += prevPoint!.y - nowPoint!.y
    if !drag {
        if abs(moveX) > kDirectionPanThreshold {
            state = .Failed
        } else {
            drag = true
        }

    }

}

 override func reset() {
    super.reset()
    moveX = 0
    moveY = 0
    drag = false
}




}

Answer 18

我采用了 Lee Goodrich 的出色 answer 并移植到 Swift 3

import UIKit
import UIKit.UIGestureRecognizerSubclass

enum PanDirection {
    case vertical
    case horizontal
}

class PanDirectionGestureRecognizer: UIPanGestureRecognizer {

    let direction : PanDirection

    init(direction: PanDirection, target: AnyObject, action: Selector) {
        self.direction = direction
        super.init(target: target, action: action)
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {

        super.touchesMoved(touches, with: event)

        if state == .began {

            let vel = velocity(in: self.view!)

            switch direction {

            case .horizontal where fabs(vel.y) > fabs(vel.x):
                state = .cancelled

            case .vertical where fabs(vel.x) > fabs(vel.y):
                state = .cancelled

            default:
                break

            }

        }
    }
}

Answer 19

我很乐意分享我的方法，因为所有其他方法都基于 UIGestureRecognizerDelegate 或子类化 UIPanGestureRecognizer。

我的方法基于运行时和 swizzling。我不能 100% 确定这种方法，但您可以自己测试和改进它。

只需一行代码即可设置任意UIPanGestureRecognizer的方向：

UITableView().panGestureRecognizer.direction = UIPanGestureRecognizer.Direction.vertical

使用pod 'UIPanGestureRecognizerDirection' 或代码：

public extension UIPanGestureRecognizer {

    override open class func initialize() {
        super.initialize()
        guard self === UIPanGestureRecognizer.self else { return }
        func replace(_ method: Selector, with anotherMethod: Selector, for clаss: AnyClass) {
            let original = class_getInstanceMethod(clаss, method)
            let swizzled = class_getInstanceMethod(clаss, anotherMethod)
            switch class_addMethod(clаss, method, method_getImplementation(swizzled), method_getTypeEncoding(swizzled)) {
            case true:
                class_replaceMethod(clаss, anotherMethod, method_getImplementation(original), method_getTypeEncoding(original))
            case false:
                method_exchangeImplementations(original, swizzled)
            }
        }
        let selector1 = #selector(UIPanGestureRecognizer.touchesBegan(_:with:))
        let selector2 = #selector(UIPanGestureRecognizer.swizzling_touchesBegan(_:with:))
        replace(selector1, with: selector2, for: self)
        let selector3 = #selector(UIPanGestureRecognizer.touchesMoved(_:with:))
        let selector4 = #selector(UIPanGestureRecognizer.swizzling_touchesMoved(_:with:))
        replace(selector3, with: selector4, for: self)
    }

    @objc private func swizzling_touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
        self.swizzling_touchesBegan(touches, with: event)
        guard direction != nil else { return }
        touchesBegan = true
    }

    @objc private func swizzling_touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        self.swizzling_touchesMoved(touches, with: event)
        guard let direction = direction, touchesBegan == true else { return }
        defer {
            touchesBegan = false
        }
        let forbiddenDirectionsCount = touches
            .flatMap({ ($0.location(in: $0.view) - $0.previousLocation(in: $0.view)).direction })
            .filter({ $0 != direction })
            .count
        if forbiddenDirectionsCount > 0 {
            state = .failed
        }
    }
}

public extension UIPanGestureRecognizer {

    public enum Direction: Int {

        case horizontal = 0
        case vertical
    }

    private struct UIPanGestureRecognizerRuntimeKeys {
        static var directions = "\(#file)+\(#line)"
        static var touchesBegan = "\(#file)+\(#line)"
    }

    public var direction: UIPanGestureRecognizer.Direction? {
        get {
            let object = objc_getAssociatedObject(self, &UIPanGestureRecognizerRuntimeKeys.directions)
            return object as? UIPanGestureRecognizer.Direction
        }
        set {
            let policy = objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC
            objc_setAssociatedObject(self, &UIPanGestureRecognizerRuntimeKeys.directions, newValue, policy)
        }
    }

    fileprivate var touchesBegan: Bool {
        get {
            let object = objc_getAssociatedObject(self, &UIPanGestureRecognizerRuntimeKeys.touchesBegan)
            return (object as? Bool) ?? false
        }
        set {
            let policy = objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC
            objc_setAssociatedObject(self, &UIPanGestureRecognizerRuntimeKeys.touchesBegan, newValue, policy)
        }
    }
}

fileprivate extension CGPoint {

    var direction: UIPanGestureRecognizer.Direction? {
        guard self != .zero else { return nil }
        switch fabs(x) > fabs(y) {
        case true:  return .horizontal
        case false: return .vertical
        }
    }

    static func -(lhs: CGPoint, rhs: CGPoint) -> CGPoint {
        return CGPoint(x: lhs.x - rhs.x, y: lhs.y - rhs.y)
    }
}

Answer 20

我试过这个：根据问题描述，这对我有用

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    if gestureRecognizer is UIPanGestureRecognizer {
        return true
    } else {
        return false
    }
}

Answer 21

SWIFT 4.2

我更进一步，做了一个方向泛手势：

enum PanDirection {
    case up
    case left
    case right
    case down
}

class PanDirectionGestureRecognizer: UIPanGestureRecognizer {
    
    fileprivate let direction: PanDirection
    
    init(direction: PanDirection, target: AnyObject, action: Selector) {
        self.direction = direction
        super.init(target: target, action: action)
    }
    
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesMoved(touches, with: event)
        
        guard state != .failed else { return }

        let vel = velocity(in: view)

        let velocities: [PanDirection: CGFloat]
            = [.up: -vel.y,
               .left: -vel.x,
               .right: vel.x,
               .down: vel.y]

        let sortedKeys = velocities.sorted { $0.1 < $1.1 }

        if let key = sortedKeys.last?.key,
            key != direction {
            state = .cancelled
        }
    }
}

（使用：https://github.com/fastred/SloppySwiper 和 https://stackoverflow.com/a/30607392/5790492）

Answer 22

PanGestureRecognizer接口包含以下定义：

unsigned int    _canPanHorizontally:1;
unsigned int    _canPanVertically:1;

我没有检查这个，但也许它可以通过子类访问。