UIGestureRecognizer
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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
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");
} 
代理协议
//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;
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 * picArray;
数组初始化为空对象
NSMutableArray * arr1 = [NSMutableArray array];
for ( int i =0; i 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;
}
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网站题目：UIKit框架（16）手势识别器-创新互联
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