IOS开发:手势识别器

1、UIGestureRecognizer 介绍

手势识别在 iOS 中非常重要，他极大地提高了移动设备的使用便捷性。iOS 系统在 3.2 以后，他提供了一些常用的手势（UIGestureRecognizer 的子类），开发者可以直接使用他们进行手势操作。UIPanGestureRecognizer（拖动）UIPinchGestureRecognizer（捏合）UIRotationGestureRecognizer（旋转）UITapGestureRecognizer（点按）UILongPressGestureRecognizer（长按）​UISwipeGestureRecognizer（轻扫）另外，可以通过继承 UIGestureRecognizer 类，实现自定义手势（手势识别器类）。PS：自定义手势时，需要 #import <UIKit/UIGestureRecognizerSubclass.h>，一般需实现如下方法：- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;

//以上方法在分类 UIGestureRecognizer (UIGestureRecognizerProtected) 中声明，更多方法声明请自行查看

2、手势状态

在六种手势识别中，只有一种手势是离散型手势，他就是 UITapGestureRecognizer。离散型手势的特点就是：一旦识别就无法取消，而且只会调用一次手势操作事件（初始化手势时指定的回调方法）。

​换句话说其他五种手势是连续型手势，而连续型手势的特点就是：会多次调用手势操作事件，而且在连续手势识别后可以取消手势。从下图可以看出两者调用操作事件的次数是不同的：

1 typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {2     UIGestureRecognizerStatePossible,   // 尚未识别是何种手势操作（但可能已经触发了触摸事件），默认状态3     UIGestureRecognizerStateBegan,      // 手势已经开始，此时已经被识别，但是这个过程中可能发生变化，手势操作尚未完成4     UIGestureRecognizerStateChanged,    // 手势状态发生转变5     UIGestureRecognizerStateEnded,      // 手势识别操作完成（此时已经松开手指）6     UIGestureRecognizerStateCancelled,  // 手势被取消，恢复到默认状态7     UIGestureRecognizerStateFailed,     // 手势识别失败，恢复到默认状态8     UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded // 手势识别完成，同UIGestureRecognizerStateEnded9 };

 对于离散型手势 UITapGestureRecgnizer 要么被识别，要么失败，点按（假设点按次数设置为1，并且没有添加长按手势）下去一次不松开则此时什么也不会发生，松开手指立即识别并调用操作事件，并且状态为3（已完成）。 但是连续型手势要复杂一些，就拿旋转手势来说，如果两个手指点下去不做任何操作，此时并不能识别手势（因为我们还没旋转）但是其实已经触发了触摸开始事件，此时处于状态0；如果此时旋转会被识别，也就会调用对应的操作事件，同时状态变成1（手势开始），但是状态1只有一瞬间；紧接着状态变为2（因为我们的旋转需要持续一会），并且重复调用操作事件（如果在事件中打印状态会重复打印2）；松开手指，此时状态变为3，并调用1次操作事件。    3、使用手势的步骤 使用手势很简单，分为三步：  创建手势识别器对象实例。创建时，指定一个回调方法，当手势开始，改变、或结束时，执行回调方法。  设置手势识别器对象实例的相关属性（可选部分）  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，那就会执行回调方法。  PS：一个手势只能对应一个 View，但是一个 View 可以有多个手势。建议在真机上测试这些手势，模拟器操作不太方便，可能导致认为手势失效的情况。（模拟器测试捏合和旋转手势时，按住 option 键，再用触摸板或鼠标操作）    4、举例说明 功能描述：  附加到两个图片视图 UIImageView 的有『拖动』、『捏合』、『旋转』、『点按』；  而『轻扫』和『自定义手势 KMGestureRecognizer』附加在根视图 UIView 中。  拖动：进行当前图片视图位置移动  捏合：进行当前图片视图缩放  旋转：进行当前图片视图角度旋转  点按：双击恢复当前图片视图的缩放、角度旋转、不透明度  长按：设置当前图片视图的不透明度为0.7  轻扫：左右轻扫设置两个图片视图为居中，同时以垂直居中的特定偏移量定位  自定义手势：挠痒功能，左右扫动共3次或以上，设置两个图片视图为居中，同时以水平居中的特定偏移量定位

 <span style="font-size:14px;"><strong>KMGestureRecognizer.h#import <UIKit/UIKit.h>typedef NS_ENUM(NSUInteger, Direction) {DirectionUnknown,DirectionLeft,DirectionRight};@interface KMGestureRecognizer : UIGestureRecognizer@property (assign, nonatomic) NSUInteger tickleCount; //挠痒次数@property (assign, nonatomic) CGPoint currentTickleStart; //当前挠痒开始坐标位置@property (assign, nonatomic) Direction lastDirection; //最后一次挠痒方向@endKMGestureRecognizer.m#import "KMGestureRecognizer.h"#import <UIKit/UIGestureRecognizerSubclass.h>@implementation KMGestureRecognizer#define kMinTickleSpacing 20.0#define kMaxTickleCount 3- (void)reset {_tickleCount = 0;_currentTickleStart = CGPointZero;_lastDirection = DirectionUnknown;if (self.state == UIGestureRecognizerStatePossible) {self.state = UIGestureRecognizerStateFailed;}}- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {UITouch *touch = [touches anyObject];_currentTickleStart = [touch locationInView:self.view]; //设置当前挠痒开始坐标位置}- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {//『当前挠痒开始坐标位置』和『移动后坐标位置』进行 X 轴值比较，得到是向左还是向右移动UITouch *touch = [touches anyObject];CGPoint tickleEnd = [touch locationInView:self.view];CGFloat tickleSpacing = tickleEnd.x - _currentTickleStart.x;Direction currentDirection = tickleSpacing < 0 ? DirectionLeft : DirectionRight;//移动的 X 轴间距值是否符合要求，足够大if (ABS(tickleSpacing) >= kMinTickleSpacing) {//判断是否有三次不同方向的动作，如果有则手势结束，将执行回调方法if (_lastDirection == DirectionUnknown ||(_lastDirection == DirectionLeft && currentDirection == DirectionRight) ||(_lastDirection == DirectionRight && currentDirection == DirectionLeft)) {_tickleCount++;_currentTickleStart = tickleEnd;_lastDirection = currentDirection;if (_tickleCount >= kMaxTickleCount && self.state == UIGestureRecognizerStatePossible) {self.state = UIGestureRecognizerStateEnded;//NSLog(@"自定义手势成功，将执行回调方法");}}}}- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {[self reset];}- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {[self reset];}@endViewController.h#import <UIKit/UIKit.h>#import "KMGestureRecognizer.h"@interface ViewController : UIViewController@property (strong, nonatomic) UIImageView *imgV;@property (strong, nonatomic) UIImageView *imgV2;@property (strong, nonatomic) KMGestureRecognizer *customGestureRecognizer;@end</strong></span>

<span style="font-size:14px;"><strong>#import "ViewController.h"@interface ViewController ()- (void)handlePan:(UIPanGestureRecognizer *)recognizer;- (void)handlePinch:(UIPinchGestureRecognizer *)recognizer;- (void)handleRotation:(UIRotationGestureRecognizer *)recognizer;- (void)handleTap:(UITapGestureRecognizer *)recognizer;- (void)handleLongPress:(UILongPressGestureRecognizer *)recognizer;- (void)handleSwipe:(UISwipeGestureRecognizer *)recognizer;- (void)handleCustomGestureRecognizer:(KMGestureRecognizer *)recognizer;- (void)bindPan:(UIImageView *)imgVCustom;- (void)bindPinch:(UIImageView *)imgVCustom;- (void)bindRotation:(UIImageView *)imgVCustom;- (void)bindTap:(UIImageView *)imgVCustom;- (void)bindLongPress:(UIImageView *)imgVCustom;- (void)bindSwipe;- (void)bingCustomGestureRecognizer;- (void)layoutUI;@end@implementation ViewController- (void)viewDidLoad {[super viewDidLoad];[self layoutUI];}- (void)didReceiveMemoryWarning {[super didReceiveMemoryWarning];// Dispose of any resources that can be recreated.}#pragma mark - 处理手势操作/***  处理拖动手势**  @param recognizer 拖动手势识别器对象实例*/- (void)handlePan:(UIPanGestureRecognizer *)recognizer {//视图前置操作[recognizer.view.superview bringSubviewToFront:recognizer.view];CGPoint center = recognizer.view.center;CGFloat cornerRadius = recognizer.view.frame.size.width / 2;CGPoint translation = [recognizer translationInView:self.view];//NSLog(@"%@", NSStringFromCGPoint(translation));recognizer.view.center = CGPointMake(center.x + translation.x, center.y + translation.y);[recognizer setTranslation:CGPointZero inView:self.view];if (recognizer.state == UIGestureRecognizerStateEnded) {//计算速度向量的长度，当他小于200时，滑行会很短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); //e.g. 397.973175, slideMult: 1.989866//基于速度和速度因素计算一个终点float slideFactor = 0.1 * slideMult;CGPoint finalPoint = CGPointMake(center.x + (velocity.x * slideFactor),center.y + (velocity.y * slideFactor));//限制最小［cornerRadius］和最大边界值［self.view.bounds.size.width - cornerRadius］，以免拖动出屏幕界限finalPoint.x = MIN(MAX(finalPoint.x, cornerRadius),self.view.bounds.size.width - cornerRadius);finalPoint.y = MIN(MAX(finalPoint.y, cornerRadius),self.view.bounds.size.height - cornerRadius);//使用 UIView 动画使 view 滑行到终点[UIView animateWithDuration:slideFactor*2delay:0options:UIViewAnimationOptionCurveEaseOutanimations:^{recognizer.view.center = finalPoint;}completion:nil];}}/***  处理捏合手势**  @param recognizer 捏合手势识别器对象实例*/- (void)handlePinch:(UIPinchGestureRecognizer *)recognizer {CGFloat scale = recognizer.scale;recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, scale, scale); //在已缩放大小基础下进行累加变化；区别于：使用 CGAffineTransformMakeScale 方法就是在原大小基础下进行变化recognizer.scale = 1.0;}/***  处理旋转手势**  @param recognizer 旋转手势识别器对象实例*/- (void)handleRotation:(UIRotationGestureRecognizer *)recognizer {recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);recognizer.rotation = 0.0;}/***  处理点按手势**  @param recognizer 点按手势识别器对象实例*/- (void)handleTap:(UITapGestureRecognizer *)recognizer {UIView *view = recognizer.view;view.transform = CGAffineTransformMakeScale(1.0, 1.0);view.transform = CGAffineTransformMakeRotation(0.0);view.alpha = 1.0;}/***  处理长按手势**  @param recognizer 点按手势识别器对象实例*/- (void)handleLongPress:(UILongPressGestureRecognizer *)recognizer {//长按的时候，设置不透明度为0.7recognizer.view.alpha = 0.7;}/***  处理轻扫手势**  @param recognizer 轻扫手势识别器对象实例*/- (void)handleSwipe:(UISwipeGestureRecognizer *)recognizer {//代码块方式封装操作方法void (^positionOperation)() = ^() {CGPoint newPoint = recognizer.view.center;newPoint.y -= 20.0;_imgV.center = newPoint;newPoint.y += 40.0;_imgV2.center = newPoint;};//根据轻扫方向，进行不同控制switch (recognizer.direction) {case UISwipeGestureRecognizerDirectionRight: {positionOperation();break;}case UISwipeGestureRecognizerDirectionLeft: {positionOperation();break;}case UISwipeGestureRecognizerDirectionUp: {break;}case UISwipeGestureRecognizerDirectionDown: {break;}}}/***  处理自定义手势**  @param recognizer 自定义手势识别器对象实例*/- (void)handleCustomGestureRecognizer:(KMGestureRecognizer *)recognizer {//代码块方式封装操作方法void (^positionOperation)() = ^() {CGPoint newPoint = recognizer.view.center;newPoint.x -= 20.0;_imgV.center = newPoint;newPoint.x += 40.0;_imgV2.center = newPoint;};positionOperation();}#pragma mark - 绑定手势操作/***  绑定拖动手势**  @param imgVCustom 绑定到图片视图对象实例*/- (void)bindPan:(UIImageView *)imgVCustom {UIPanGestureRecognizer *recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:selfaction:@selector(handlePan:)];[imgVCustom addGestureRecognizer:recognizer];}/***  绑定捏合手势**  @param imgVCustom 绑定到图片视图对象实例*/- (void)bindPinch:(UIImageView *)imgVCustom {UIPinchGestureRecognizer *recognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:selfaction:@selector(handlePinch:)];[imgVCustom addGestureRecognizer:recognizer];//[recognizer requireGestureRecognizerToFail:imgVCustom.gestureRecognizers.firstObject];}/***  绑定旋转手势**  @param imgVCustom 绑定到图片视图对象实例*/- (void)bindRotation:(UIImageView *)imgVCustom {UIRotationGestureRecognizer *recognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleRotation:)];[imgVCustom addGestureRecognizer:recognizer];}/***  绑定点按手势**  @param imgVCustom 绑定到图片视图对象实例*/- (void)bindTap:(UIImageView *)imgVCustom {UITapGestureRecognizer *recognizer = [[UITapGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleTap:)];//使用一根手指双击时，才触发点按手势识别器recognizer.numberOfTapsRequired = 2;recognizer.numberOfTouchesRequired = 1;[imgVCustom addGestureRecognizer:recognizer];}/***  绑定长按手势**  @param imgVCustom 绑定到图片视图对象实例*/- (void)bindLongPress:(UIImageView *)imgVCustom {UILongPressGestureRecognizer *recognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];recognizer.minimumPressDuration = 0.5; //设置最小长按时间；默认为0.5秒[imgVCustom addGestureRecognizer:recognizer];}/***  绑定轻扫手势；支持四个方向的轻扫，但是不同的方向要分别定义轻扫手势*/- (void)bindSwipe {//向右轻扫手势UISwipeGestureRecognizer *recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleSwipe:)];recognizer.direction = UISwipeGestureRecognizerDirectionRight; //设置轻扫方向；默认是 UISwipeGestureRecognizerDirectionRight，即向右轻扫[self.view addGestureRecognizer:recognizer];[recognizer requireGestureRecognizerToFail:_customGestureRecognizer]; //设置以自定义挠痒手势优先识别//向左轻扫手势recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleSwipe:)];recognizer.direction = UISwipeGestureRecognizerDirectionLeft;[self.view addGestureRecognizer:recognizer];[recognizer requireGestureRecognizerToFail:_customGestureRecognizer]; //设置以自定义挠痒手势优先识别}/***  绑定自定义挠痒手势；判断是否有三次不同方向的动作，如果有则手势结束，将执行回调方法*/- (void)bingCustomGestureRecognizer {//当 recognizer.state 为 UIGestureRecognizerStateEnded 时，才执行回调方法 handleCustomGestureRecognizer://_customGestureRecognizer = [KMGestureRecognizer new];_customGestureRecognizer = [[KMGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleCustomGestureRecognizer:)];[self.view addGestureRecognizer:_customGestureRecognizer];}- (void)layoutUI {//图片视图 _imgVUIImage *img = [UIImage imageNamed:@"Emoticon_tusiji_icon"];CGFloat cornerRadius = img.size.width;_imgV = [[UIImageView alloc] initWithImage:img];_imgV.frame = CGRectMake(20.0, 20.0,cornerRadius * 2, cornerRadius * 2);_imgV.userInteractionEnabled = YES;_imgV.layer.masksToBounds = YES;_imgV.layer.cornerRadius = cornerRadius;_imgV.layer.borderWidth = 2.0;_imgV.layer.borderColor = [UIColor grayColor].CGColor;[self.view addSubview:_imgV];//图片视图 _imgV2img = [UIImage imageNamed:@"Emoticon_tusiji_icon2"];cornerRadius = img.size.width;_imgV2 = [[UIImageView alloc] initWithImage:img];_imgV2.frame = CGRectMake(20.0, 40.0 + _imgV.frame.size.height,cornerRadius * 2, cornerRadius * 2);_imgV2.userInteractionEnabled = YES;_imgV2.layer.masksToBounds = YES;_imgV2.layer.cornerRadius = cornerRadius;_imgV2.layer.borderWidth = 2.0;_imgV2.layer.borderColor = [UIColor orangeColor].CGColor;[self.view addSubview:_imgV2];[self bindPan:_imgV];[self bindPinch:_imgV];[self bindRotation:_imgV];[self bindTap:_imgV];[self bindLongPress:_imgV];[self bindPan:_imgV2];[self bindPinch:_imgV2];[self bindRotation:_imgV2];[self bindTap:_imgV2];[self bindLongPress:_imgV2];//为了处理手势识别优先级的问题，这里需先绑定自定义挠痒手势[self bingCustomGestureRecognizer];[self bindSwipe];}@end</strong></span>