UIGestureRecognizer手势识别器

监听触摸事件的做法

• 如果想监听一个view上面的触摸事件,一个做法是
    ➢ 自定义⼀个view
    ➢ 实现view的touches方法,在方法内部实现具体处理代码

• 通过touches方法监听view触摸事件,有很明显的几个缺点
    ➢ 必须得自定义view
    ➢ 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
    ➢ 不容易区分用户的具体手势行为

另一个做法是手势识别器

• 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

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

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

• UIGestureRecognizer是⼀一个抽象类,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,⽤用于缩放)

➢ UIPanGestureRecognizer(拖拽)

➢ UISwipeGestureRecognizer(轻扫)

➢ UIRotationGestureRecognizer(旋转)

➢ UILongPressGestureRecognizer(长按)

手势识别器的用法
• 每一个手势识别器的用法都差不多,比如UITapGestureRecognizer的使用步骤如下

➢ 创建手势识别器对象

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];

➢ 设置手势识别器对象的具体属性

// 连续敲击2次

tap.numberOfTapsRequired = 2;

// 需要2根手指一起敲击

tap.numberOfTouchesRequired = 2;

➢ 添加手势识别器到对应的view上

[self.iconView addGestureRecognizer:tap];

➢ 监听手势的触发

[tap addTarget:self action:@selector(tapIconView:)];

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,

// ⼿势取消恢⾄Possible状态

UIGestureRecognizerStateCancelled

}

//
//  ViewController.m
//  gestureRecognizer
//
//  Created by ys on 15/11/21.
//  Copyright (c) 2015年 ys. All rights reserved.
//

#import "ViewController.h"

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

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];

/**
手势识别器新建->添加->监听
*/
//    //新建手势识别器,这些识别器均继承自UIGestureRecognizer
//    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]init];
//    //将手势识别器添加到view
//    [self.imageView addGestureRecognizer:tap];
//    //监听手势识别器
//    [tap addTarget:self action:@selector(tapAction)];

/*
*点击识别器
*/
[self.imageView addGestureRecognizer:[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapAction)]];

/*
*长按识别器
*/
[self.imageView addGestureRecognizer:[[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(longPressAction)]];

/*
*滑动识别器
*/
UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeAction)];
/*
*滑动方向
*/
swipe.direction = UISwipeGestureRecognizerDirectionLeft;
[self.imageView addGestureRecognizer:swipe];

/*
*旋转识别器
*/
UIRotationGestureRecognizer *rotate = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(rotationAction:)];
rotate.delegate = self;
[self.imageView addGestureRecognizer:rotate];

/**
*  缩放识别器
*/
UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(pinchAction:)];
pinch.delegate = self;
[self.imageView addGestureRecognizer:pinch];

/**
*移动识别器
*/
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panAction:)];
[self.imageView addGestureRecognizer:pan];

}

-(void)tapAction
{
NSLog(@"tap------");
}

-(void)longPressAction
{
NSLog(@"longPress------");
}

-(void)swipeAction
{
NSLog(@"swipe----left");
}

-(void)rotationAction:(UIRotationGestureRecognizer *)rotate
{
rotate.view.transform = CGAffineTransformRotate(rotate.view.transform, rotate.rotation);
/**
*  清零rotation可以解决旋转度数累积(数据冗余)造成旋转速度过快的bug
*/
rotate.rotation = 0;
}

-(void)pinchAction:(UIPinchGestureRecognizer *)pinch
{
pinch.view.transform = CGAffineTransformScale(pinch.view.transform, pinch.scale, pinch.scale);
pinch.scale = 1;//同rotation一样解决数据冗余问题
}

-(void)panAction:(UIPanGestureRecognizer *)pan
{
CGPoint point = [pan translationInView:pan.view];
CGPoint center = pan.view.center;
center.x += point.x;
center.y += point.y;
pan.view.center = center;
[pan setTranslation:CGPointZero inView:pan.view];//清零位移
}

/**
*  手势识别器代理方法shouldRecognizeSimultaneouslyWithGestureRecognizer
*
*  @return 是否可以两个识别器同时发生作用,此demo同时监听旋转和缩放
*/
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}

@end