UIKit框架（16）手势识别器

2025-02-12 技术教程

UIGestureRecognizer

利用手势识别器，能够轻松识别用户在某个view上面做一些常见的手势

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 捏合手势

UIPanGestureRecognizer 拖拽

UISwipeGestureRecognizer 轻扫

UIRotationGestureRecognizer 旋转

UILongPressGestureRecognizer 长按

手势识别器使用的一般步骤（以敲击手势为例）

创建手势识别器对象

UITapGestureRecognizer*tap=[[UITapGestureRecognizeralloc]init];

设置手势识别器对象的具体属性：

//连续敲击2次且两根手指敲击时响应tap.numberOfTapsRequired=2;tap.numberOfTouchesRequired=2;

添加手势识别器到view上：

[self.iconViewaddGestureRecognizer:tap];

监听手势的触发：

[tapaddTarger:selfaction:@selector(tapIconView:)];

实现触发的方法

-(void)tapIconView:(UITapGestureRecognizer*)tapGR{NSLog(@"tap响应");}

手势识别器的状态

手势识别器的代理

代理协议<UIGestureRecognizerDelegate>

//是否接受这个touch对象（默认返回YES），这个代理方法在一个触摸事件产生时先调用-(BOOL)gestureRecognizer:(UIGestureRecognizer*)gestureRecognizershouldReceiveTouch:(UITouch*)touch;//确定两个类似的手势识别器是否同时处理-(BOOL)gestureRecognizer:(UIGestureRecognizer*)gestureRecognizershouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer*)otherGestureRecognizer;

示例：UITabBarController的滑动手势控制

1）UITabBarController子类，保存所有子控制器的截图

添加UIImage对象数组

@property(nonatomic,strong)NSMutableArray<UIImage*>*picArray;

数组初始化为空对象

NSMutableArray*arr1=[NSMutableArrayarray];for(inti=0;i<self.viewControllers.count;i++){[arr1addObject:[NSNullnull]];}self.picArray=[arr1mutableCopy];

重写selectedIndex的setter方法：切换子控制器前，截图保存

-(void)setSelectedIndex:(NSUInteger)selectedIndex{//截图操作floatwidth=[UIScreenmainScreen].bounds.size.width;floatheight=[UIScreenmainScreen].bounds.size.height;UIGraphicsBeginImageContext(CGSizeMake(width,height));CGContextRefcontext=UIGraphicsGetCurrentContext();[[UIApplicationsharedApplication].keyWindow.layerrenderInContext:context];UIImage*p_w_picpath=UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();//截图保存到截图数组NSLog(@"selectedIndex=%ld",self.selectedIndex);self.picArray[self.selectedIndex]=p_w_picpath;[supersetSelectedIndex:selectedIndex];}

提供方法，返回当前子控制器的前后两个子控制器的截图

-(UIImage*)p_w_picpathForCurrentViewControllerLeft{if(self.selectedIndex==0){returnnil;}returnself.picArray[self.selectedIndex-1];}-(UIImage*)p_w_picpathForCurrentViewControllerRight{if(self.selectedIndex==self.viewControllers.count-1){returnnil;}returnself.picArray[self.selectedIndex+1];}

2）添加子控制器的共用父类

UITabBarController的所有子控制器的类型就是继承自一个共用父类

父类中添加滑动手势识别器

UIPanGestureRecognizer*gr1=[[UIPanGestureRecognizeralloc]init];[gr1addTarget:selfaction:@selector(panGR:)];[self.viewaddGestureRecognizer:gr1];

父类中添加UIImageView属性，用于存储当前页面左右两个截图p_w_picpathView

@property(nonatomic,weak)UIImageView*ivLeft;@property(nonatomic,weak)UIImageView*ivRight;

手势识别器：手势开始时，当前view左右放置截图

UIImage*imgLeft=[((ViewController*)self.tabBarController)p_w_picpathForCurrentViewControllerLeft];if(imgLeft==nil){self.ivLeft=nil;}else{if([imgLeftisKindOfClass:[NSNullclass]]){//一张白***片imgLeft=[UIImagep_w_picpathNamed:@"white_bg"];}UIImageView*ivLeft=[[UIImageViewalloc]initWithImage:imgLeft];self.ivLeft=ivLeft;[self.viewaddSubview:ivLeft];self.ivLeft.frame=CGRectMake(-self.view.frame.size.width,0,self.view.frame.size.width,self.view.frame.size.height);}UIImage*imgRight=[((ViewController*)self.tabBarController)p_w_picpathForCurrentViewControllerRight];if(imgRight==nil){self.ivRight=nil;}else{if([imgRightisKindOfClass:[NSNullclass]]){imgRight=[UIImagep_w_picpathNamed:@"white_bg"];}UIImageView*ivRight=[[UIImageViewalloc]initWithImage:imgRight];self.ivRight=ivRight;[self.viewaddSubview:self.ivRight];self.ivRight.frame=CGRectMake(self.view.frame.size.width,0,self.view.frame.size.width,self.view.frame.size.height);}

手势识别器：手势滑动式时，当前view随之滑动

if(p.x>0&&self.ivLeft==nil){return;}if(p.x<0&&self.ivRight==nil){return;}self.view.transform=CGAffineTransformMakeTranslation(p.x,0);

手势识别器，手势结束时，根据位置确定是否切换子控制器

if(self.view.transform.tx>self.view.frame.size.width/2&&self.ivLeft!=nil){self.view.transform=CGAffineTransformIdentity;self.tabBarController.selectedIndex--;if(self.ivLeft!=nil){[self.ivLeftremoveFromSuperview];self.ivLeft=nil;}if(self.ivRight!=nil){[self.ivRightremoveFromSuperview];self.ivRight=nil;}return;}if(self.view.transform.tx<-self.view.frame.size.width/2&&self.ivRight!=nil){self.view.transform=CGAffineTransformIdentity;self.tabBarController.selectedIndex++;if(self.ivLeft!=nil){[self.ivLeftremoveFromSuperview];self.ivLeft=nil;}if(self.ivRight!=nil){[self.ivRightremoveFromSuperview];self.ivRight=nil;}return;}[UIViewanimateWithDuration:0.5animations:^{self.view.transform=CGAffineTransformIdentity;}completion:^(BOOLfinished){if(self.ivLeft!=nil){[self.ivLeftremoveFromSuperview];self.ivLeft=nil;}if(self.ivRight!=nil){[self.ivRightremoveFromSuperview];self.ivRight=nil;}}];