【iOS进阶】【触摸事件】手势识别功能

一、监听触摸事件的做法　　　　　　　　　　　　　　　　　　

1>如果想监听一个view上面的触摸事件，之前的做法是

　　1.自定义一个view

　　2.实现view的touches方法，在方法内部实现具体处理代码

2>通过touches方法监听view触摸事件，有很明显的几个缺点

　　1.必须得自定义view

　　2.由于是在view内部的touches方法中监听触摸事件，因此默认情况下，无法让其他外界对象监听view的触摸事件

　　3.不容易区分用户的具体手势行为

3>iOS 3.2之后，苹果推出了手势识别功能（Gesture Recognizer），在触摸事件处理方面，大大简化了开发者的开发难度

二、UIGestureRecognizer　　　　　　　　　　　　　　　

1>为了完成手势识别，必须借助于手势识别器----UIGestureRecognizer

　　利用UIGestureRecognizer，能轻松识别用户在某个view上面做的一些常见手势

2>UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，使用它的子类才能处理具体的手势

　　　　UITapGestureRecognizer(敲击)

　　　　UIPinchGestureRecognizer(捏合，用于缩放)

　　　　UIPanGestureRecognizer(拖拽)

　　　　UISwipeGestureRecognizer(轻扫)

　　　　UIRotationGestureRecognizer(旋转)

　　　　UILongPressGestureRecognizer(长按)

3>手势识别的状态

typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
    // 没有触摸事件发生，所有手势识别的默认状态
    UIGestureRecognizerStatePossible,
    // 一个手势已经开始但尚未改变或者完成时
    UIGestureRecognizerStateBegan,
    // 手势状态改变
    UIGestureRecognizerStateChanged,
    // 手势完成
    UIGestureRecognizerStateEnded,
    // 手势取消，恢复至Possible状态
    UIGestureRecognizerStateCancelled, 
    // 手势失败，恢复至Possible状态
    UIGestureRecognizerStateFailed,
    // 识别到手势识别
    UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded
};

三、UIGestureRecognizer的具体用法　　　　　　　　　　　　

1>敲击（UITapGestureRecognizer）

#import "ViewController.h"

@interface ViewController () <UIGestureRecognizerDelegate>

@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //可交互
    self.imageView.userInteractionEnabled = YES;
    //可多点触控
    self.imageView.multipleTouchEnabled = YES;
    [self textTap];

}

#pragma mark - UIGestureRecognizer代理方法 - 主要用于拦截触摸点
/**
 *  当点击view的时候，会先调用这个方法
 */
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{
    CGPoint pos = [touch locationInView:touch.view];
    NSLog(@"%@",NSStringFromCGPoint(pos));
}

#pragma mark - 敲击手势
/**
 *  常用的做法
 */
-(void)textTap{
#warning 手势识别器－敲击
    //1.创建手势识别器对象
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];
    
    //连续敲击指定次数，手势才能识别成功
    tap.numberOfTapsRequired = 2;
    //两根手指一起敲
    tap.numberOfTouchesRequired = 2;
    
    //2.添加手势识别器到对应的view
    [self.imageView addGestureRecognizer:tap];
    //3.添加监听方法（识别到了对应的手势，就会调用监听方法）
    [tap addTarget:self action:@selector(tapView)];
}

-(void)tapView{
    NSLog(@"hehe");
}

/**
 *  简化的做法
 */
-(void)textTap2{
    //默认一根手指敲击一次
    UIGestureRecognizer *tap =[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapView)];
    tap.delegate = self;
    [self.imageView addGestureRecognizer:tap];
}

@end

2>清扫（UISwipeGestureRecognizer）、长按（UILongPressGestureRecognizer）

#import "ViewController.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIView *redView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    UISwipeGestureRecognizer *swipeUp = [[UISwipeGestureRecognizer alloc] 
　　　　　　　　　　　　　　　　　　　　initWithTarget:self action:@selector(swpieView)];
    UISwipeGestureRecognizer *swipeDown = [[UISwipeGestureRecognizer alloc] 
　　　　　　　　　　　　　　　　　　　　initWithTarget:self action:@selector(swpieView)];
    UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] 
　　　　　　　　　　　　　　　　　　　　initWithTarget:self action:@selector(swpieView)];
    UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] 
　　　　　　　　　　　　　　　　　　　　initWithTarget:self action:@selector(swpieView)];
    
    //设置清扫方向清扫方向
    //上
    swipeUp.direction = UISwipeGestureRecognizerDirectionUp;
    //下
    swipeDown.direction = UISwipeGestureRecognizerDirectionDown;
    //左
    swipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;
    //右
    swipeRight.direction = UISwipeGestureRecognizerDirectionRight;
    
    [self.redView addGestureRecognizer:swipeUp];
    [self.redView addGestureRecognizer:swipeDown];
    [self.redView addGestureRecognizer:swipeLeft];
    [self.redView addGestureRecognizer:swipeRight];
}

#pragma mark － 清扫
-(void)swpieView{
    NSLog(@"清扫了view");
}

#pragma mark － 长按
-(void)textLongPress{
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] 
　　　　　　　　　　　　　　　　　　　　　initWithTarget:self action:@selector(longPressView)];
    //至少长按多少秒
    longPress.minimumPressDuration = 2.0;
    //在触发手势之前，指定像素内有效
    longPress.allowableMovement =50;
    
    [self.redView addGestureRecognizer:longPress];

}
-(void)longPressView{
    NSLog(@"长按了view");
}
@end

1>旋转（UIRotationGestureRecognizer）、缩放（UIPinchGestureRecognizer）

#import "ViewController.h"

@interface ViewController () <UIGestureRecognizerDelegate>
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self testPinch];
    [self testRotate];
    
}
#pragma mark － 手势识别器的代理方法
/**
 *  是否允许多个手势识别器同时有效
 *  Simultaneously : 同时地
 */
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer 
　　　　shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{
    return YES;
}

#pragma mark  - 缩放
-(void)testPinch{
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchView:)];
    pinch.delegate =self;
    [self.imageView addGestureRecognizer:pinch];
}

-(void)pinchView:(UIPinchGestureRecognizer *)pinch{
    //scale-缩放比例
    pinch.view.transform = CGAffineTransformScale(pinch.view.transform,pinch.scale,pinch.scale);
    pinch.scale = 1;
    NSLog(@"缩放-----%f",pinch.scale);
}

#pragma mark  - 旋转
-(void)testRotate{
    UIRotationGestureRecognizer *rotate = [[UIRotationGestureRecognizer alloc] 
　　　　　　　　　　　　　　　　　　　　initWithTarget:self action:@selector(rotateView:)];
    rotate.delegate = self;
    [self.imageView addGestureRecognizer:rotate];
}

//触发了手势就会把手势对象传给你
-(void)rotateView:(UIRotationGestureRecognizer *)rotate{
    rotate.view.transform = CGAffineTransformRotate(rotate.view.transform, rotate.rotation);
#warning 这个设置很重要，每转一次就要清0一次
    rotate.rotation = 0;
    NSLog(@"旋转");
}

@end

1>缩放（UIPanGestureRecognizer）

#import "ViewController.h"

@interface ViewController () <UIGestureRecognizerDelegate>
@property (weak, nonatomic) IBOutlet UIView *yellowView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panView:)];
    [self.yellowView addGestureRecognizer:pan];
}

-(void)panView:(UIPanGestureRecognizer *)pan{
    switch (pan.state) {
        case UIGestureRecognizerStateBegan://开始出发手势
            break;
        case UIGestureRecognizerStateEnded://手势结束
            break;
        default:
            break;
    }
    
    //获取在view上面挪动的距离
    CGPoint pos = [pan translationInView:pan.view];
    CGPoint center = pan.view.center;
    center.x += pos.x;
    center.y += pos.y;
    pan.view.center = center;
    //清空移动的距离
    [pan setTranslation:CGPointZero inView:pan.view];
    
    NSLog(@"拖拽--------%@", NSStringFromCGPoint(pos));
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    NSLog(@"View最后的位置------%@",NSStringFromCGPoint(self.yellowView.center));
}

@end