UIKit框架（16）手势识别器

爱被打了一巴掌 2022-01-16 13:21 239阅读 0赞

*  **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 = [[UITapGestureRecognizer alloc] 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.iconView addGestureRecognizer:tap];

监听手势的触发 ：

[tap addTarger:self action:@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**

[![wKioL1bT\_AKy4xUqAAKIbtrZTyg751.png][wKioL1bT_AKy4xUqAAKIbtrZTyg751.png]][wKioL1bT_AKy4xUqAAKIbtrZTyg751.png]

*  **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*) gestureRecognizer shouldReceiveTouch:(UITouch*) touch;
    //确定两个类似的手势识别器是否同时处理
    - (BOOL) gestureRecognizer:(UIGestureRecognizer*) gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(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 = [NSMutableArray array];
    for ( int i =0; i<self.viewControllers.count; i++) {
        [arr1 addObject:[NSNull null]];
    }
    self.picArray = [arr1 mutableCopy];

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
        float width = [UIScreen mainScreen].bounds.size.width;
        float height = [UIScreen mainScreen].bounds.size.height;
        UIGraphicsBeginImageContext(CGSizeMake(width, height));
        CGContextRef context = UIGraphicsGetCurrentContext();
        [[UIApplication sharedApplication].keyWindow.layer renderInContext: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;
    
        [super setSelectedIndex: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 ) {
            return nil;
        }
        return self.picArray[self.selectedIndex-1];
    }
    - (UIImage *) p_w_picpathForCurrentViewControllerRight
    {
        if ( self.selectedIndex == self.viewControllers.count - 1 ) {
            return nil;
        }
        return self.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 = [[UIPanGestureRecognizer alloc] init];
    [gr1 addTarget:self action:@selector(panGR:)];
    [self.view addGestureRecognizer: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 ( [imgLeft isKindOfClass:[NSNull class]] ) {
            //一张白***片
            imgLeft = [UIImage p_w_picpathNamed:@"white_bg"];
        }
        UIImageView * ivLeft = [[UIImageView alloc] initWithImage:imgLeft];
        self.ivLeft = ivLeft;
        [self.view addSubview: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 ( [imgRight isKindOfClass:[NSNull class]] ) {
            imgRight = [UIImage p_w_picpathNamed:@"white_bg"];
        }
        UIImageView * ivRight= [[UIImageView alloc] initWithImage:imgRight];
        self.ivRight = ivRight;
        [self.view addSubview: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.ivLeft removeFromSuperview];
            self.ivLeft = nil;
        }
        if ( self.ivRight != nil ) {
            [self.ivRight removeFromSuperview];
            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.ivLeft removeFromSuperview];
            self.ivLeft = nil;
        }
        if ( self.ivRight != nil ) {
            [self.ivRight removeFromSuperview];
            self.ivRight = nil;
        }
        return ;
    }
    
    [UIView animateWithDuration:0.5 animations:^{
        self.view.transform = CGAffineTransformIdentity;
    } completion:^(BOOL finished) {
        if ( self.ivLeft != nil ) {
            [self.ivLeft removeFromSuperview];
            self.ivLeft = nil;
        }
        if ( self.ivRight != nil ) {
            [self.ivRight removeFromSuperview];
            self.ivRight = nil;
        }
    }];

转载于:https://blog.51cto.com/annmeng/1746138

[wKioL1bT_AKy4xUqAAKIbtrZTyg751.png]: https://s1.51cto.com/wyfs02/M00/7C/A0/wKioL1bT_AKy4xUqAAKIbtrZTyg751.png