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:
- 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。
- 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:
- UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]];
- snakeImageView.frame = CGRectMake(50, 50, 100, 160);
- UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]
- initWithTarget:self
- action:@selector(handlePan:)];
- [snakeImageView addGestureRecognizer:panGestureRecognizer];
- [self.view setBackgroundColor:[UIColor whiteColor]];
- [self.view addSubview:snakeImageView];
新建一个ImageView,然后添加手势
回调方法:
- - (void) handlePan:(UIPanGestureRecognizer*) recognizer
- {
- CGPoint translation = [recognizer translationInView:self.view];
- recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
- recognizer.view.center.y + translation.y);
- [recognizer setTranslation:CGPointZero inView:self.view];
-
- }
4、Pinch缩放手势
- UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc]
- initWithTarget:self
- action:@selector(handlePinch:)];<p class="p1">[<span class="s1">snakeImageView</span> <span class="s2">addGestureRecognizer</span>:pinchGestureRecognizer];</p>
- - (void) handlePinch:(UIPinchGestureRecognizer*) recognizer
- {
- recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);
- recognizer.scale = 1;
- }
5、Rotation旋转手势
- UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]
- initWithTarget:self
- action:@selector(handleRotate:)];
- [snakeImageView addGestureRecognizer:rotateRecognizer];
- - (void) handleRotate:(UIRotationGestureRecognizer*) recognizer
- {
- recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);
- recognizer.rotation = 0;
- }
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
- - (void)viewDidLoad
- {
- [super viewDidLoad];
-
- UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]];
- UIImageView *dragonImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"dragon.png"]];
- snakeImageView.frame = CGRectMake(120, 120, 100, 160);
- dragonImageView.frame = CGRectMake(50, 50, 100, 160);
- [self.view addSubview:snakeImageView];
- [self.view addSubview:dragonImageView];
-
- for (UIView *view in self.view.subviews) {
- UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]
- initWithTarget:self
- action:@selector(handlePan:)];
-
- UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc]
- initWithTarget:self
- action:@selector(handlePinch:)];
-
- UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]
- initWithTarget:self
- action:@selector(handleRotate:)];
-
- [view addGestureRecognizer:panGestureRecognizer];
- [view addGestureRecognizer:pinchGestureRecognizer];
- [view addGestureRecognizer:rotateRecognizer];
- [view setUserInteractionEnabled:YES];
- }
- [self.view setBackgroundColor:[UIColor whiteColor]];
- }
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?
- - (void) handlePan:(UIPanGestureRecognizer*) recognizer
- {
- CGPoint translation = [recognizer translationInView:self.view];
- recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
- recognizer.view.center.y + translation.y);
- [recognizer setTranslation:CGPointZero inView:self.view];
-
- 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;
- NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);
-
- 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 animations:^{
- recognizer.view.center = finalPoint;
- } completion:nil];
-
- }
-
代码实现解析:
- 计算速度向量的长度(估计大部分都忘了)这些知识了。
- 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
- 基于速度和速度因素计算一个终点
- 确保终点不会跑出父View的边界
- 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,
- @interface ViewController : UIViewController<UIGestureRecognizerDelegate>
- @end
并在协议这个方法里返回YES。
- -(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
- {
- return YES;
- }
把self作为代理设置给手势:
- panGestureRecognizer.delegate = self;
- pinchGestureRecognizer.delegate = self;
- 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。
- - (AVAudioPlayer *)loadWav:(NSString *)filename {
- NSURL * url = [[NSBundle mainBundle] URLForResource:filename withExtension:@"wav"];
- NSError * error;
- AVAudioPlayer * player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
- if (!player) {
- NSLog(@"Error loading %@: %@", url, error.localizedDescription);
- } else {
- [player prepareToPlay];
- }
- return player;
- }
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。
- #import <UIKit/UIKit.h>
- #import <AVFoundation/AVFoundation.h>
-
- @interface ViewController : UIViewController<UIGestureRecognizerDelegate>
- @property (strong) AVAudioPlayer * chompPlayer;
- @property (strong) AVAudioPlayer * hehePlayer;
-
- @end
- - (void)handleTap:(UITapGestureRecognizer *)recognizer {
- [self.chompPlayer play];
- }
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:
- [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:
- – touchesBegan:withEvent:
- – touchesMoved:withEvent:
- – touchesEnded:withEvent:
- - touchesCancelled:withEvent:
新建一个类,继承UIGestureRecognizer,代码如下:
.h文件
- #import <UIKit/UIKit.h>
- typedef enum {
- DirectionUnknown = 0,
- DirectionLeft,
- DirectionRight
- } Direction;
-
- @interface HappyGestureRecognizer : UIGestureRecognizer
- @property (assign) int tickleCount;
- @property (assign) CGPoint curTickleStart;
- @property (assign) Direction lastDirection;
-
- @end
.m文件
- #import "HappyGestureRecognizer.h"
- #import <UIKit/UIGestureRecognizerSubclass.h>
- #define REQUIRED_TICKLES 2
- #define MOVE_AMT_PER_TICKLE 25
-
- @implementation HappyGestureRecognizer
-
- - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
- UITouch * touch = [touches anyObject];
- self.curTickleStart = [touch locationInView:self.view];
- }
-
- - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
-
-
- UITouch * touch = [touches anyObject];
- CGPoint ticklePoint = [touch locationInView:self.view];
- CGFloat moveAmt = ticklePoint.x - self.curTickleStart.x;
- Direction curDirection;
- if (moveAmt < 0) {
- curDirection = DirectionLeft;
- } else {
- curDirection = DirectionRight;
- }
- if (ABS(moveAmt) < MOVE_AMT_PER_TICKLE) return;
-
-
- if (self.lastDirection == DirectionUnknown ||
- (self.lastDirection == DirectionLeft && curDirection == DirectionRight) ||
- (self.lastDirection == DirectionRight && curDirection == DirectionLeft)) {
-
-
- self.tickleCount++;
- self.curTickleStart = ticklePoint;
- self.lastDirection = curDirection;
-
-
-
- if (self.state == UIGestureRecognizerStatePossible && self.tickleCount > REQUIRED_TICKLES) {
- [self setState:UIGestureRecognizerStateEnded];
- }
- }
-
- }
-
- - (void)reset {
- self.tickleCount = 0;
- self.curTickleStart = CGPointZero;
- self.lastDirection = DirectionUnknown;
- if (self.state == UIGestureRecognizerStatePossible) {
- [self setState:UIGestureRecognizerStateFailed];
- }
- }
-
- - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
- {
- [self reset];
- }
-
- - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
- {
- [self reset];
- }
-
- @end
调用自定义手势和上面一样,回到这样写:
- - (void)handleHappy:(HappyGestureRecognizer *)recognizer{
- [self.hehePlayer play];
- }
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。
参考:http://www.raywenderlich.com/6567/uigesturerecognizer-tutorial-in-ios-5-pinches-pans-and-more
例子代码: http://download.csdn.net/detail/totogo2010/5094059
容芳志 (http://blog.csdn.net/totogo2010)
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