【发布时间】：2013-07-22 16:43:22
【问题描述】：
我试图让用户在完成 UIPanGestureRecognizer 方法时获取正在动画的 UIView。我目前能够使用 touchesBegan 和视图的表示层来停止视图并将其居中放置在手指下方。但我希望用户能够重新触发 UIPanGestureRecognizer 方法，而无需抬起手指并在 UIView 上替换它。
我已经为这个挑战工作了一周左右，并且在 SO 和其他地方浏览了各种搜索字符串，阅读了 Ray Wenderlich 的教程等，但仍然没有找到解决方案。看起来我正在尝试做与这个似乎未解决的问题类似的事情：
iOS - UIPanGestureRecognizer : drag during animation
我刚刚开始使用 UIView 动画块，还没有深入研究 CABasicAnimation 的工作。是否可以通过某种方式更改下面的代码来做我想做的事？
提前谢谢你。
在 FlingViewController.h 中：
#import <UIKit/UIKit.h>
@interface FlingViewController : UIViewController <UIGestureRecognizerDelegate>
{
UIView *myView;
}
@property (nonatomic, weak) UIView *myView;
@end
在 FlingViewController.m 中：
#import "FlingViewController.h"
#import <QuartzCore/QuartzCore.h>
@interface FlingViewController ()
@end
@implementation FlingViewController
@synthesize myView = _myView;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
// Allocate and init view
myView = [[UIView alloc] initWithFrame:CGRectMake(self.view.center.x - 50,
self.view.center.y - 50,
100, 100)];
// Set view background color
[myView setBackgroundColor:[UIColor purpleColor]];
// Create pan gesture recognizer
UIPanGestureRecognizer *gesture = [[UIPanGestureRecognizer alloc]
initWithTarget:self action:@selector(handleGesture:)];
// Add gesture recognizer to view
gesture.delegate = self;
[myView addGestureRecognizer:gesture];
// Add myView as subview
[self.view addSubview:myView];
NSLog(@"myView added");
}
- (void)handleGesture:(UIPanGestureRecognizer *)recognizer
{
if ((recognizer.state == UIGestureRecognizerStateBegan) ||
(recognizer.state == UIGestureRecognizerStateChanged))
{
[recognizer.view.layer removeAllAnimations];
CGPoint translation = [recognizer translationInView:self.view];
recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}
else if (recognizer.state == UIGestureRecognizerStateEnded)
{
CGPoint velocity = [recognizer velocityInView:self.view];
CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));
CGFloat slideMult = magnitude / 200;
float slideFactor = 0.1 * slideMult;
CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor),
recognizer.view.center.y + (velocity.y * slideFactor));
finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width);
finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height);
[UIView animateWithDuration:slideFactor * 2
delay:0
options:(UIViewAnimationOptionCurveEaseOut|
UIViewAnimationOptionAllowUserInteraction |
UIViewAnimationOptionBeginFromCurrentState)
animations:^{
recognizer.view.center = finalPoint;
}
completion:^(BOOL finished){
NSLog(@"Animation complete");
}];
}
}
// Currently, this method will detect when user touches
// myView's presentationLayer and will center that view under the finger
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint touchPoint = [touch locationInView:self.view];
if ([[myView.layer presentationLayer] hitTest:touchPoint])
{
NSLog(@"Touched!");
[myView.layer removeAllAnimations];
myView.center = touchPoint;
// *** NOTE ***
// At this point, I want the user to be able to fling
// the view around again without having to lift the finger
// and replace it on the view; i.e. when myView is moving
// and the user taps it, it should stop moving and follow
// user's pan gesture again
// Similar to unresolved SO question:
// https://stackoverflow.com/questions/13234234/ios-uipangesturerecognizer-drag-during-animation
}
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
【问题讨论】：
标签： cocoa-touch animation uiview uipangesturerecognizer touchesbegan