手势识别功能（Gesture Recognizer）
1. 手势识别概念
a. iOS 3.2之后，苹果推出了手势识别功能（GestureRecognizer），在触摸事件处理方面，大大简化了开发者的开发难度。
b. 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. 手势识别功能
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. 手势识别用法
a. 每一个手势识别器的用法都这三步：
1> 创建一个手势的对象;
2> 把手势的对象添加到需要手势的view当中;
3> 实现手势的方法;
b. 用法的具体介绍
#import "ViewController.h"
@interfaceViewController ()
@property (weak,nonatomic) IBOutletUIImageView* imageView;
@end
@implementationViewController
- (void)viewDidLoad
{
[superviewDidLoad];
//敲击手势
// 创建敲击手势的对象
UITapGestureRecognizer* tap = [[UITapGestureRecognizeralloc] initWithTarget:selfaction:@selector(tap:)];
// 几根手指
tap.numberOfTouchesRequired = 2;
// 点几次
tap.numberOfTapsRequired = 2;
// 对imageView添加手势
[self.imageViewaddGestureRecognizer:tap];
//轻扫手势
// 创建轻扫手势的对象
UISwipeGestureRecognizer* swipe = [[UISwipeGestureRecognizeralloc]initWithTarget:selfaction:@selector(swipe:)];
UISwipeGestureRecognizer* swipe1 = [[UISwipeGestureRecognizeralloc]initWithTarget:selfaction:@selector(swipe:)];
// 设置手势方向
swipe.direction = UISwipeGestureRecognizerDirectionLeft;
swipe.direction = UISwipeGestureRecognizerDirectionRight;
// 对imageView添加手势
[self.imageViewaddGestureRecognizer:swipe];
[self.imageViewaddGestureRecognizer:swipe1];
//长按手势
UILongPressGestureRecognizer* longPress = [[UILongPressGestureRecognizeralloc]initWithTarget:selfaction:@selector(longPress:)];
// 长按多长时间执行方法
longPress.minimumPressDuration = 2;
// 误差
longPress.allowableMovement = 10;
// 对imageView添加手势
[self.imageViewaddGestureRecognizer:longPress];
//旋转
UIRotationGestureRecognizer* rotation = [[UIRotationGestureRecognizeralloc]initWithTarget:selfaction:@selector(rotation:)];
[self.imageViewaddGestureRecognizer:rotation];
//捏合，用于缩放
UIPinchGestureRecognizer* pinch = [[UIPinchGestureRecognizeralloc]initWithTarget:selfaction:@selector(pinch:)];
[self.imageViewaddGestureRecognizer:pinch];
//拖拽
UIPanGestureRecognizer* pan = [[UIPanGestureRecognizeralloc] initWithTarget:selfaction:@selector(pan:)];
[self.imageViewaddGestureRecognizer:pan];
}
// 敲击
- (void)tap:(UITapGestureRecognizer*)sender
{
NSLog(@"tap");
}
// 轻扫
- (void)swipe:(UISwipeGestureRecognizer*)sender
{
if (sender.direction == UISwipeGestureRecognizerDirectionLeft){
NSLog(@"left");
}
else {
NSLog(@"right");
}
}
// 长按
- (void)longPress:(UILongPressGestureRecognizer*)sender
{
// 想让长按开始的时候执行某个代码，需要判断手势的状态
if (sender.state == UIGestureRecognizerStateBegan){
NSLog(@"longPress");
}
}
UIGestureRecognizerState手势状态是一个枚举
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
};
// 旋转
- (void)rotation:(UIRotationGestureRecognizer*)sender
{
self.imageView.transform= CGAffineTransformRotate(self.imageView.transform, sender.rotation);
sender.rotation = 0;
}
// 捏合
- (void)pinch:(UIPinchGestureRecognizer*)sender
{
self.imageView.transform= CGAffineTransformScale(self.imageView.transform, sender.scale,sender.scale);
sender.scale = 1;
}
// 拖拽
- (void)pan:(UIPanGestureRecognizer*)sender
{
//手指拖动imageView位移时的实时位移量；
CGPoint p = [sender translationInView:self.imageView];
NSLog(@"%@",NSStringFromCGPoint(p));
//将imageView按照上面的实时位移量进行位移；
self.imageView.transform= CGAffineTransformTranslate(self.imageView.transform, p.x,p.y);
//每一次实时位移的时候，都让它的位移量归零；
[sender setTranslation:CGPointZeroinView:self.imageView];
}