长按后滑动

Question

好的，我正在帮助将安卓游戏转换为 iOS。该游戏基于 2048，但使用字母而不是数字。我有很多工作，但仍在学习 Objective C/iOS 的怪癖。到目前为止，我的瓷砖/网格正在工作，运动正在工作等，但我需要一些帮助。目标是允许用户长按一个拼贴来选择它，然后将他们的手指滑到相邻的拼贴上以开始拼写一个单词。我已经实现了长按部分，但我对如何让它长按然后滑动有点茫然。最重要的是，我已经有了一个允许用户移动图块的滑动。在这里搜索时，我看到了关于子类化的建议，所以我想我需要子类化 UISwipeGestureRecognizer 方法。我已经安装了同时手势识别器，但不知道从哪里开始。

所以，有几个问题。

1. 最好的方法是什么？实现每个UISwipeGestureRecognizer的子类？

2. 我当前的滑动检测会干扰吗？ （现在滑动本身会在滑动方向上移动图块）

3. 我想我需要做一个（如果长按）然后激活子类滑动方法？

4. 回答上述问题的任何示例都会有很大帮助。我不是要你为我做这件事，但至少可以为我指明一个大致的方向。谢谢！

代码如下。

//  Grid.m
#import "Grid.h"
#import "Tile.h"

- (void)didLoadFromCCB {
    // listen for swipes to the left
    UISwipeGestureRecognizer * swipeLeft= [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeLeft)];
    swipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;
    [[[CCDirector sharedDirector] view] addGestureRecognizer:swipeLeft];

    // listen for swipes to the right
    UISwipeGestureRecognizer * swipeRight= [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeRight)];
    swipeRight.direction = UISwipeGestureRecognizerDirectionRight;
    [[[CCDirector sharedDirector] view] addGestureRecognizer:swipeRight];

    // listen for swipes up
    UISwipeGestureRecognizer * swipeUp= [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeUp)];
    swipeUp.direction = UISwipeGestureRecognizerDirectionUp;
    [[[CCDirector sharedDirector] view] addGestureRecognizer:swipeUp];

    // listen for swipes down
    UISwipeGestureRecognizer * swipeDown= [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeDown)];
    swipeDown.direction = UISwipeGestureRecognizerDirectionDown;
    [[[CCDirector sharedDirector] view] addGestureRecognizer:swipeDown];

    // listen for long press
    UILongPressGestureRecognizer *longpress = [[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(onLongPress:)];
    [longpress setMinimumPressDuration:0.5];
    [[[CCDirector sharedDirector] view] addGestureRecognizer:longpress];
}

- (void)swipeLeft {
    [self move:ccp(-1, 0)];
}
- (void)swipeRight {
    [self move:ccp(1, 0)];
}
- (void)swipeDown {
    [self move:ccp(0, -1)];
}
- (void)swipeUp {
    [self move:ccp(0, 1)];
}

// detect longpress, convert to NodeSpace and check if touch location is within tile boundingbox. If yes, set background white, text black.
- (void)onLongPress:(UILongPressGestureRecognizer *) recognizer {
    CGPoint touchPoint = [[CCDirector sharedDirector] convertToGL:[recognizer locationInView:[recognizer view]]];
    touchPoint = [self convertToNodeSpace:touchPoint];

    if (recognizer.state == UIGestureRecognizerStateBegan) {
        for (Tile *tile in self.children) {
            if([tile isKindOfClass:[Tile class]]) {

                CGRect tileBoundingBox = tile.boundingBox;
                if (CGRectContainsPoint(tileBoundingBox, touchPoint)) {

                    tile.backgroundNode.color = [CCColor whiteColor];
                    tile.valueLabel.color = [CCColor blackColor];
                    [self spellWord:tile.value];
                    [_word setString:[_word lowercaseString]];
                    CCLOG(@"%@", _word);
                }
            }
        }
    }

    if (recognizer.state == UIGestureRecognizerStateChanged) {

    }

    if (recognizer.state == UIGestureRecognizerStateEnded) {
        for (Tile *tile in self.children) {
            if([tile isKindOfClass:[Tile class]]) {

                CGRect tileBoundingBox = tile.boundingBox;
                if (CGRectContainsPoint(tileBoundingBox, touchPoint)) {
                    tile.backgroundNode.color = [tile getColor:tile.value];
                    tile.valueLabel.color = [self getContrastColor:r green:g blue:b];

                }
            }
        }
    }
}

// allow for simultaneous gestures
- (BOOL)gestureRecognizer:(UIGestureRecognizer *) recognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
    return YES;
}

Answer 1

回答您的问题：

1. 这并没有让我觉得这是一种需要子类化UILongPressGestureRecognizer 的编码情况。话虽如此，子类化通常是清理视图控制器代码的好方法，因此您在视图控制器类中没有血腥的手势识别器代码。但是这里没有什么（据我所知）需要这样做。您通常会深入研究手势识别器的子类，其中需要一些特殊的自定义行为（例如，如果某些复杂的标准失败，则手势会失败）。不过，在我走这条路之前，我会先看看你是否可以通过标准手势实现所需的用户体验。

2. 我可以看到滑动手势相互干扰的唯一原因是您已指定 shouldRecognizeSimultaneouslyWithGestureRecognizer 应返回 YES。这用于您需要同时运行多个识别器的情况，这在这里似乎没有必要（并且只是问题的根源）。

   我不清楚您是真的想要一个单独的滑动手势还是只想要一个手势（“长按并拖动”）。但是，如果您需要单独的滑动手势，您通常会通过指定 requireGestureRecognizerToFail 来指定手势识别器的相对优先级（例如，让滑动需要长按才能失败才能识别滑动）。但如果你真的只有一个手势（“长按并拖动”），那么只需要一个手势识别器。

3. 似乎没有必要。如果您想在长按被识别后检测移动，您可以将“长按后移动”代码放在UIGestureRecognizedStateChanged 的UIGestureRecognizedStateChanged 的if 语句中，这发生在识别长按之后，但在用户抬起手指之前。 UILongPressGestureRecognizer 是一个连续的手势识别器，在最初识别出手势后，随着用户手指的移动，它将继续获得更新。

---

我知道您没有要求提供代码，但如果您想要滑动手势以及长按手势（本质上是拿起并拖动它的想法），您可以执行以下操作.请注意，我使滑动手势要求长按失败，因此如果用户长按，则优先，否则它会滑动。但是您可能根本不需要滑动手势，所以如果您不需要它，只需将其完全移除即可：

#import <UIKit/UIGestureRecognizerSubclass.h>

- (void)viewDidLoad {
    [super viewDidLoad];

    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
    [self.view addGestureRecognizer:longPress];

    // if you needed a second gesture, a swipe, completely distinct from the long press and drag
    // gesture, you could add it like so:
    //
    // UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
    // [swipe requireGestureRecognizerToFail:longPress];
    // // do additional swipe configuration
    // [self.view addGestureRecognizer:swipe];
}

- (void)handleSwipe:(UISwipeGestureRecognizer *)gesture
{
    // do your separate swipe stuff here
}

- (void)handleLongPress:(UILongPressGestureRecognizer *)gesture
{
    static UIView *tileToMove;
    static CGPoint startCenter;
    static CGPoint startLocation;

    CGPoint location = [gesture locationInView:self.view];

    switch (gesture.state) {
        case UIGestureRecognizerStateBegan:
        {
            // find the tile

            tileToMove = [self findTileToMove:location];
            if (tileToMove) {
                // if found, capture state ...

                startCenter = tileToMove.center;
                startLocation = location;

                // ... and animate "pick up tile", so the user gets positive feedback
                // that the drag/swipe portion of the gesture is starting.

                [UIView animateWithDuration:0.25 animations:^{
                    tileToMove.transform = CGAffineTransformMakeScale(1.2, 1.2);
                }];
            } else {
                gesture.state = UIGestureRecognizerStateFailed;
            }
            break;
        }
        case UIGestureRecognizerStateChanged:
        {
            // move the tile as the user's finger moves

            CGPoint translate = CGPointMake(location.x - startLocation.x, location.y - startLocation.y);

            // note, if you want to constrain the translation to be, for example, on the
            // x-axis alone, you could do something like:
            //
            // CGPoint translate = CGPointMake(location.x - startLocation.x, 0);

            tileToMove.center = CGPointMake(startCenter.x + translate.x, startCenter.y + translate.y);
            break;
        }
        case UIGestureRecognizerStateEnded:
        {
            // animate "drop the tile"

            [UIView animateWithDuration:0.25 animations:^{
                tileToMove.transform = CGAffineTransformIdentity;

                // if you want the tile to "snap" to some location having let it go,
                // set the `center` or `frame` here.
            }];

            // clear our variables, just in case

            tileToMove = nil;
            startCenter = CGPointZero;
            startLocation = CGPointZero;
            break;
        }
        default:
            break;
    }
}

- (UIView *)findTileToMove:(CGPoint)location
{
    for (UIView *tile in self.tiles) {
        if (CGRectContainsPoint(tile.frame, location)) {
            return tile;
        }
    }

    return nil;
}

这可能与您正在寻找的 UI 不太完全相同，但它说明了：

1. 如何有两个手势，其中一个需要另一个失败才能在手势之间建立优先级（如果你想要两个不同的手势，显然只有一个问题，你可能不这样做）；

2. 没有shouldRecognizeSimultaneouslyWithGestureRecognizer 方法，因为我不希望它们同时被识别。请注意，仅当您确实需要两个手势时才需要，您可能需要也可能不需要；和

3. 如何让长按不仅能识别初始长按，还能识别随后的滑动/拖动动作。