捏合与拖动手势实现视图的缩放拖动以及任一边界拖进屏幕自动回弹

2019-11-07 23:58:38

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来源：转载

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实现这个功能也是被逼无奈，项目需要缩放移动有很多小页签的WKWebView，尝试了UIScrollView，但是很不理想，因为webview需要侧滑和上下滑动，所以缩放拖动绝大部分都无法触发，只得采用手势实现。在网上查阅了大量资料，终于实现了该功能，废话不多说，上代码：

1、定义缩放倍数和偏移量

// 缩放倍数#define minScale 1#define maxScale 2// 偏移量#define Offset 0

2、定义需要用到的属性

@PRoperty (nonatomic,strong) UIImageView *imgView;// 要缩放的视图// 缩放@property (nonatomic, assign) CGFloat lastScale;// 上一次缩放的比例@property (nonatomic, strong) UipinchGestureRecognizer *pinch;// 捏合手势@property (nonatomic, strong) UIPanGestureRecognizer *pan;// 平移手势

3、初始化视图、手势，并设置手势

_imgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"2.jpg"]]; _imgView.frame = self.view.frame; _imgView.userInteractionEnabled = YES; [self.view addSubview:_imgView]; _pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchAction:)]; _pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panAction:)]; [_imgView addGestureRecognizer:_pinch]; [_imgView addGestureRecognizer:_pan];

4、设置锚点

- (void)adjustAnchorPointForGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer{ //UIGestureRecognizerStateBegan意味着手势已经被识别 if (gestureRecognizer.state ==UIGestureRecognizerStateBegan) { //手势发生在哪个view上 UIView *piece = gestureRecognizer.view; //获得当前手势在view上的位置。 CGPoint locationInView = [gestureRecognizer locationInView:piece]; piece.layer.anchorPoint =CGPointMake(locationInView.x / piece.bounds.size.width, locationInView.y / piece.bounds.size.height); //根据在view上的位置设置锚点。 //防止设置完锚点过后，view的位置发生变化，相当于把view的位置重新定位到原来的位置上。 CGPoint locationInSuperview = [gestureRecognizer locationInView:piece.superview]; piece.center = locationInSuperview; }}

5、缩放方法

- (void)pinchAction:(UIPinchGestureRecognizer *)gestureRecognizer{ UIGestureRecognizerState state = [gestureRecognizer state]; if(state == UIGestureRecognizerStateBegan) { _lastScale = [gestureRecognizer scale]; } if (gestureRecognizer.scale > 1) { [self adjustAnchorPointForGestureRecognizer:gestureRecognizer]; }else{ _imgView.layer.anchorPoint =CGPointMake(0.5, 0.5); _imgView.center = self.view.center; } CGFloat currentScale = [[[gestureRecognizer view].layer valueForKeyPath:@"transform.scale"] floatValue]; if (state == UIGestureRecognizerStateBegan || state == UIGestureRecognizerStateChanged) { CGFloat newScale = 1 - (_lastScale - [gestureRecognizer scale]); newScale = MIN(newScale, maxScale / currentScale); newScale = MAX(newScale, minScale / currentScale); CGAffineTransform transform = CGAffineTransformScale([[gestureRecognizer view] transform], newScale, newScale); NSLog(@"newScale = %f,currentScale = %f",newScale,currentScale); [gestureRecognizer view].transform = transform; _lastScale = [gestureRecognizer scale]; } if (state == UIGestureRecognizerStateEnded) { if (currentScale >= minScale && currentScale <= minScale + 0.1) { [_imgView removeGestureRecognizer:_pan]; }else if(currentScale > minScale + 0.1 && currentScale <= maxScale){ [_imgView addGestureRecognizer:_pan]; } }}

6、拖动方法

- (void)panAction:(UIPanGestureRecognizer *)gestureRecognizer{ if (gestureRecognizer.state == UIGestureRecognizerStateBegan || gestureRecognizer.state == UIGestureRecognizerStateChanged) { if (!(_imgView.frame.origin.x == 0 && _imgView.frame.origin.y == 0 && _imgView.frame.size.width == self.view.frame.size.width && _imgView.frame.size.height == self.view.frame.size.height)) { CGPoint translation = [gestureRecognizer translationInView:self.view]; gestureRecognizer.view.center = CGPointMake(gestureRecognizer.view.center.x + translation.x, gestureRecognizer.view.center.y + translation.y); [gestureRecognizer setTranslation:CGPointZero inView:self.view]; } } CGRect rect = _imgView.frame; if (_imgView.frame.origin.x > 0 + Offset) {//左边进入屏幕 NSLog(@"左边进入屏幕"); [UIView animateWithDuration:0.25 animations:^{ CGPoint point = CGPointMake(gestureRecognizer.view.center.x - gestureRecognizer.view.frame.origin.x, gestureRecognizer.view.center.y); gestureRecognizer.view.center = point; }]; }else if (CGRectGetMaxX(rect) < self.view.frame.size.width + Offset){ NSLog(@"右边进入屏幕"); [UIView animateWithDuration:0.25 animations:^{ CGRect newRect = CGRectOffset(_imgView.frame, self.view.frame.size.width - CGRectGetMaxX(_imgView.frame), 0); _imgView.frame = newRect; }]; } if (_imgView.frame.origin.y > 0 + Offset) {//上边进入屏幕 NSLog(@"上边进入屏幕"); [UIView animateWithDuration:0.25 animations:^{ CGPoint point = CGPointMake(gestureRecognizer.view.center.x, gestureRecognizer.view.center.y - gestureRecognizer.view.frame.origin.y); gestureRecognizer.view.center = point; }]; }else if(CGRectGetMaxY(rect) < self.view.frame.size.height + Offset){ NSLog(@"下边进入屏幕"); [UIView animateWithDuration:0.25 animations:^{ CGRect newRect = CGRectOffset(_imgView.frame, 0, self.view.frame.size.height - CGRectGetMaxY(_imgView.frame)); _imgView.frame = newRect; }]; }}

手势实现也是万不得已才用的，如果有哪位大神解决了UIScrollView缩放有多个侧滑页签，并且可以上下滑动的WKWebView，请给我留言，相互交流，万分感谢。

转载请注明出处，万分感谢！

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