摘要:本文将带你了解手势识别在iOS上非常重要,手势操作移动设备的重要特征,极大的增加了移动设备使用便捷性。希望本文对大家学IOS有所帮助。
1、UIGestureRecognizer介绍
手势识别在iOS上非常重要,手势操作移动设备的重要特征,极大的增加了移动设备使用便捷性。
iOS系统在3.2以后,为方便开发这使用一些常用的手势,提供了UIGestureRecognizer类。手势识别UIGestureRecognizer类是个抽象类,下面的子类是具体的手势,开发这可以直接使用这些手势识别。
· UITapGestureRecognizer
· UIPinchGestureRecognizer
· UIRotationGestureRecognizer
· UISwipeGestureRecognizer
· UIPanGestureRecognizer
· UILongPressGestureRecognizer
上面的手势对应的操作是:
· Tap(点一下)
· Pinch(二指往內或往外拨动,平时经常用到的缩放)
· Rotation(旋转)
· Swipe(滑动,快速移动)
· Pan (拖移,慢速移动)
· LongPress(长按)
UIGestureRecognizer的继承关系如下:
2、使用手势的步骤
使用手势很简单,分为两步:
00001. 创建手势实例。当创建手势时,指定一个回调方法,当手势开始,改变、或结束时,回调方法被调用。
00002. 添加到需要识别的View中。每个手势只对应一个View,当屏幕触摸在View的边界内时,如果手势和预定的一样,那就会回调方法。
ps:一个手势只能对应一个View,但是一个View可以有多个手势。
建议在真机上运行这些手势,模拟器操作不太方便,可能导致你认为手势失效。
3、Pan 拖动手势:
[cpp] view plain copy 1. UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]]; 2. snakeImageView.frame = CGRectMake(50, 50, 100, 160); 3. UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] 4. initWithTarget:self 5. action:@selector(handlePan:)]; 6. [snakeImageView addGestureRecognizer:panGestureRecognizer]; 7. [self.view setBackgroundColor:[UIColor whiteColor]]; 8. [self.view addSubview:snakeImageView]; 新建一个ImageView,然后添加手势 回调方法: [cpp] view plain copy 1. - (void) handlePan:(UIPanGestureRecognizer*) recognizer 2. { 3. CGPoint translation = [recognizer translationInView:self.view]; 4. recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, 5. recognizer.view.center.y + translation.y); 6. [recognizer setTranslation:CGPointZero inView:self.view]; 7. 8. } 4、Pinch缩放手势 [cpp] view plain copy 1. UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] 2. initWithTarget:self 3. action:@selector(handlePinch:)];<p class="p1">[<span class="s1">snakeImageView</span> <span class="s2">addGestureRecognizer</span>:pinchGestureRecognizer];</p> [cpp] view plain copy 1. - (void) handlePinch:(UIPinchGestureRecognizer*) recognizer 2. { 3. recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale); 4. recognizer.scale = 1; 5. } 5、Rotation旋转手势 [cpp] view plain copy 1. UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc] 2. initWithTarget:self 3. action:@selector(handleRotate:)]; 4. [snakeImageView addGestureRecognizer:rotateRecognizer]; [cpp] view plain copy 1. - (void) handleRotate:(UIRotationGestureRecognizer*) recognizer 2. { 3. recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation); 4. recognizer.rotation = 0; 5. }
添加了这几个手势后,运行看效果,程序中的imageView放了一个
/^\/^\
_|__| O|
\/ /~ \_/ \
\____|__________/ \
\_______ \
`\ \ \
| | \
/ / \
/ / \\
/ / \ \
/ / \ \
/ / _----_ \ \
/ / _-~ ~-_ | |
( ( _-~ _--_ ~-_ _/ |
\ ~-____-~ _-~ ~-_ ~-_-~ /
~-_ _-~ ~-_ _-~
~--______-~ ~-___-~
的图片,在模拟器上拖动是没问题的。缩放和旋转有点问题,估计是因为在模拟器上的模拟的两个接触点距离在imageView的边界外了,所以操作无效果。
建议在真机上运行这个手势。
在模拟器上缩放和选择的操作技巧:
可以把imageView的frame值设置大一点,按住alt键,按下触摸板(不按下不行),这样就可以旋转和缩放了。
6、添加第二个ImagView并添加手势
记住:一个手势只能添加到一个View,两个View当然要有两个手势的实例了
[cpp] view plain copy 1. - (void)viewDidLoad 2. { 3. [super viewDidLoad]; 4. 5. UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]]; 6. UIImageView *dragonImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"dragon.png"]]; 7. snakeImageView.frame = CGRectMake(120, 120, 100, 160); 8. dragonImageView.frame = CGRectMake(50, 50, 100, 160); 9. [self.view addSubview:snakeImageView]; 10. [self.view addSubview:dragonImageView]; 11. 12. for (UIView *view in self.view.subviews) { 13. UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] 14. initWithTarget:self 15. action:@selector(handlePan:)]; 16. 17. UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] 18. initWithTarget:self 19. action:@selector(handlePinch:)]; 20. 21. UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc] 22. initWithTarget:self 23. action:@selector(handleRotate:)]; 24. 25. [view addGestureRecognizer:panGestureRecognizer]; 26. [view addGestureRecognizer:pinchGestureRecognizer]; 27. [view addGestureRecognizer:rotateRecognizer]; 28. [view setUserInteractionEnabled:YES]; 29. } 30. [self.view setBackgroundColor:[UIColor whiteColor]]; 31. }
多添加了一条龙的view,两个view都能接收上面的三种手势。运行效果如下:
7、拖动(pan手势)速度(以较快的速度拖放后view有滑行的效果)
如何实现呢?
00001. 监视手势是否结束
00002. 监视触摸的速度
[cpp] view plain copy
1. - (void) handlePan:(UIPanGestureRecognizer*) recognizer 2. { 3. CGPoint translation = [recognizer translationInView:self.view]; 4. recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, 5. recognizer.view.center.y + translation.y); 6. [recognizer setTranslation:CGPointZero inView:self.view]; 7. 8. if (recognizer.state == UIGestureRecognizerStateEnded) { 9. 10. CGPoint velocity = [recognizer velocityInView:self.view]; 11. CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y)); 12. CGFloat slideMult = magnitude / 200; 13. NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult); 14. 15. float slideFactor = 0.1 * slideMult; // Increase for more of a slide 16. CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor), 17. recognizer.view.center.y + (velocity.y * slideFactor)); 18. finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width); 19. finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height); 20. 21. [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{ 22. recognizer.view.center = finalPoint; 23. } completion:nil]; 24. 25. } 26.
代码实现解析:
00001. 计算速度向量的长度(估计大部分都忘了)这些知识了。
00002. 如果速度向量小于200,那就会得到一个小于的小数,那么滑行会很短
00003. 基于速度和速度因素计算一个终点
00004. 确保终点不会跑出父View的边界
00005. 使用UIView动画使view滑动到终点
运行后,快速拖动图像view放开会看到view还会在原来的方向滑行一段路。
8、同时触发两个view的手势
手势之间是互斥的,如果你想同时触发蛇和龙的view,那么需要实现协议
UIGestureRecognizerDelegate, [cpp] view plain copy 1. @interface ViewController : UIViewController<UIGestureRecognizerDelegate> 2. @end 并在协议这个方法里返回YES。 [cpp] view plain copy 1. -(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer 2. { 3. return YES; 4. } 把self作为代理设置给手势: [cpp] view plain copy 1. panGestureRecognizer.delegate = self; 2. pinchGestureRecognizer.delegate = self; 3. rotateRecognizer.delegate = self; 这样可以同时拖动或旋转缩放两个view了。 9、tap点击手势 这里为了方便看到tap的效果,当点击一下屏幕时,播放一个声音。 为了播放声音,我们加入AVFoundation.framework这个框架。 [cpp] view plain copy 1. - (AVAudioPlayer *)loadWav:(NSString *)filename { 2. NSURL * url = [[NSBundle mainBundle] URLForResource:filename withExtension:@"wav"]; 3. NSError * error; 4. AVAudioPlayer * player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error]; 5. if (!player) { 6. NSLog(@"Error loading %@: %@", url, error.localizedDescription); 7. } else { 8. [player prepareToPlay]; 9. } 10. return player; 11. } 我会在最后例子代码给出完整代码,添加手势的步骤和前面一样的。 [cpp] view plain copy 1. #import <UIKit/UIKit.h> 2. #import <AVFoundation/AVFoundation.h> 3. 4. @interface ViewController : UIViewController<UIGestureRecognizerDelegate> 5. @property (strong) AVAudioPlayer * chompPlayer; 6. @property (strong) AVAudioPlayer * hehePlayer; 7. 8. @end [cpp] view plain copy 1. - (void)handleTap:(UITapGestureRecognizer *)recognizer { 2. [se
lf.chompPlayer play];
3. }
运行,点一下某个图,就会播放一个咬东西的声音。
不过这个点击播放声音有点缺陷,就是在慢慢拖动的时候也会播放。这使得两个手势重合了。怎么解决呢?使用手势的:requireGestureRecognizerToFail方法。
10、手势的依赖性
在viewDidLoad的循环里添加这段代码:
[cpp] view plain copy
1. [tapRecognizer requireGestureRecognizerToFail:panGestureRecognizer];
意思就是,当如果pan手势失败,就是没发生拖动,才会出发tap手势。这样如果你有轻微的拖动,那就是pan手势发生了。tap的声音就不会发出来了。
11、自定义手势
自定义手势继承:UIGestureRecognizer,实现下面的方法:
[cpp] view plain copy
1. – touchesBegan:withEvent: 2. – touchesMoved:withEvent: 3. – touchesEnded:withEvent: 4. - touchesCancelled:withEvent: 新建一个类,继承UIGestureRecognizer,代码如下: .h文件 [cpp] view plain copy 1. #import <UIKit/UIKit.h> 2. typedef enum { 3. DirectionUnknown = 0, 4. DirectionLeft, 5. DirectionRight 6. } Direction; 7. 8. @interface HappyGestureRecognizer : UIGestureRecognizer 9. @property (assign) int tickleCount; 10. @property (assign) CGPoint curTickleStart; 11. @property (assign) Direction lastDirection; 12. 13. @end .m文件 [cpp] view plain copy 1. #import "HappyGestureRecognizer.h" 2. #import <UIKit/UIGestureRecognizerSubclass.h> 3. #define REQUIRED_TICKLES 2 4. #define MOVE_AMT_PER_TICKLE 25 5. 6. @implementation HappyGestureRecognizer 7. 8. - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 9. UITouch * touch = [touches anyObject]; 10. self.curTickleStart = [touch locationInView:self.view]; 11. } 12. 13. - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 14. 15. // Make sure we've moved a minimum amount since curTickleStart 16. UITouch * touch = [touches anyObject]; 17. CGPoint ticklePoint = [touch locationInView:self.view]; 18. CGFloat moveAmt = ticklePoint.x - self.curTickleStart.x; 19. Direction curDirection; 20. if (moveAmt < 0) { 21. curDirection = DirectionLeft; 22. } else { 23. curDirection = DirectionRight; 24. } 25. if (ABS(moveAmt) < MOVE_AMT_PER_TICKLE) return; 26. 27. // 确认方向改变了 28. if (self.lastDirection == DirectionUnknown || 29. (self.lastDirection == DirectionLeft && curDirection == DirectionRight) || 30. (self.lastDirection == DirectionRight && curDirection == DirectionLeft)) { 31. 32. // 挠痒次数 33. self.tickleCount++; 34. self.curTickleStart = ticklePoint; 35. self.lastDirection = curDirection; 36. 37. // 一旦挠痒次数超过指定数,设置手势为结束状态 38. // 这样回调函数会被调用。 39. if (self.state == UIGestureRecognizerStatePossible && self.tickleCount > REQUIRED_TICKLES) { 40. [self setState:UIGestureRecognizerStateEnded]; 41. } 42. } 43. 44. } 45. 46. - (void)reset { 47. self.tickleCount = 0; 48. self.curTickleStart = CGPointZero; 49. self.lastDirection = DirectionUnknown; 50. if (self.state == UIGestureRecognizerStatePossible) { 51. [self setState:UIGestureRecognizerStateFailed]; 52. } 53. } 54. 55. - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 56. { 57. [self reset]; 58. } 59. 60. - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event 61. { 62. [self reset]; 63. } 64. 65. @end
调用自定义手势和上面一样,回到这样写:
[cpp] view plain copy
1. - (void)handleHappy:(HappyGestureRecognizer *)recognizer{
2. [self.hehePlayer play];
3. }
手势成功后播放呵呵笑的声音。
在真机上运行,按住某个view,快速左右拖动,就会发出笑的声音了。
代码解析:
先获取起始坐标:curTickleStart
通过和ticklePoint的x值对比,得出当前的放下是向左还是向右。再算出移动的x的值是否比MOVE_AMT_PER_TICKLE距离大,如果太则返回。
再判断是否有三次是不同方向的动作,如果是则手势结束,回调。
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