iOS手势识别的详细介绍

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   （点一下）
• UIPinchGestureRecognizer   （二指往內或往外拨动，平时经常用到的缩放）
• UIRotationGestureRecognizer   （旋转）
• UISwipeGestureRecognizer   （滑动，快速移动）
• UIPanGestureRecognizer   （拖移，慢速移动）
• UILongPressGestureRecognizer   （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：

1. 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。
2. 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];

  

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]];
}

 

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？

1. 监视手势是否结束
2. 监视触摸的速度

- (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; // Increase for more of a slide
        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：

1. 计算速度向量的长度（估计大部分都忘了）这些知识了。
2. 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
3. 基于速度和速度因素计算一个终点
4. 确保终点不会跑出父View的边界
5. 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点击手势播放声音

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。

 

– touchesBegan:withEvent:
– touchesMoved:withEvent:
– touchesEnded:withEvent:
- touchesCancelled:withEvent:

 

11、自定义手势

自定义手势继承：UIGestureRecognizer，实现下面的方法：

 

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 {

    // Make sure we've moved a minimum amount since curTickleStart
    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;

    // 确认方向改变了
    if (self.lastDirection == DirectionUnknown ||
        (self.lastDirection == DirectionLeft && curDirection == DirectionRight) ||
        (self.lastDirection == DirectionRight && curDirection == DirectionLeft)) {

        // 挠痒次数
        self.tickleCount++;
        self.curTickleStart = ticklePoint;
        self.lastDirection = curDirection;

        // 一旦挠痒次数超过指定数，设置手势为结束状态
        // 这样回调函数会被调用。
        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://blog.csdn.net/sunyazhou13/article/details/15504107

例子代码：http://download.csdn.net/detail/totogo2010/5094059