Gesture手势 转自http://blog.sina.com.cn/s/blog_8a6c97b5010106zq.html

tap是指轻触手势。类似鼠标操作的点击。从iOS 3.2版本开始支持完善的手势api：

• tap：轻触
• long press：在一点上长按
• pinch：两个指头捏或者放的操作
• pan：手指的拖动
• swipe：手指在屏幕上很快的滑动
• rotation：手指反向操作

  这为开发者编写手势识别操作，提供了很大的方便，想想之前用android写手势滑动的代码（编写android简单的手势切换视图示例），尤其感到幸福。

  这里写一个简单的tap操作。在下面视图的蓝色视图内增加对tap的识别：

  

  ?

  当用手指tap蓝色视图的时候，打印日志输出：

  

  代码很简单，首先要声明tap的recognizer：

  UITapGestureRecognizer *recognizer=[[UITapGestureRecognizer alloc]initWithTarget:selfaction:@selector(handleTapFrom:)];?
  [infoView addGestureRecognizer:recognizer];?
  [recognizer release];

  在这里：

  • initWithTarget:self，要引用到Controller，因为一般这部分代码写在controller中，用self；
  • action:@selector(handleTapFrom:)，赋值一个方法名，用于当手势事件发生后的回调；
  • [infoViewaddGestureRecognizer:recognizer]，为view注册这个手势识别对象，这样当手指在该视图区域内，可引发手势，之外则不会引发

    对应的回调方法：

    -(void)handleTapFrom:(UITapGestureRecognizer*)recognizer{?
    ???NSLog(@">>>tapit");?
    }

    controller相关方法完整的代码（包含了一些与本文无关的视图构建代码）：

    // Implement loadView to create a view hierarchy programmatically,without using a nib.?
    - (void)loadView {?
    ???//去掉最顶端的状态拦?
    ???[[UIApplication sharedApplication] setStatusBarHidden:YESwithAnimation: UIStatusBarAnimationSlide];?
    ????
    ??? UIImage*image=[UIImage imageNamed:@"3.jpg"];?
    ????
    ???//创建背景视图?
    ???self.view=[[UIView alloc] initWithFrame:[[UIScreen mainScreen]applicationFrame]];?
    ??? UIImageView*backgroudView=[[UIImageView alloc]initWithImage:image];?
    ??? [self.viewaddSubview:backgroudView];?
    ????
    ????
    ????
    ??? UIView*bottomView=[[UIView alloc]?initWithFrame:CGRectMake(0, 1024-70, 768,70)];?
    ???bottomView.backgroundColor=[UIColorgrayColor];?
    ???bottomView.alpha=0.8;?
    ????
    ??? //UIButton*backButton=[[UIButton alloc] initWithFrame:CGRectMake(10, 10, 100,40)];?
    ??? UIButton*backButton=[UIButton buttonWithType:UIButtonTypeRoundedRect];?
    ??? [backButtonsetTitle:@"ok"forState:UIControlStateNormal];?
    ???backButton.frame=CGRectMake(10, 15, 100,40);?
    ????
    ??? [bottomViewaddSubview:backButton];?
    ????
    ??? [self.viewaddSubview:bottomView];?
    ????
    ??? UIView*infoView=[[UIView alloc] initWithFrame:CGRectMake(200, 700,768-400, 70)];?
    ???infoView.backgroundColor=[UIColorblueColor];?
    ???infoView.alpha=0.6;?
    ???infoView.layer.cornerRadius=6;?
    ???infoView.layer.masksToBounds=YES;?
    ??? [self.viewaddSubview:infoView];?
    ????
    ???UITapGestureRecognizer *recognizer=[[UITapGestureRecognizer alloc]initWithTarget:selfaction:@selector(handleTapFrom:)];?
    ??? [infoViewaddGestureRecognizer:recognizer];?
    ??? [recognizerrelease];?
    }

    -(void)handleTapFrom:(UITapGestureRecognizer*)recognizer{?
    ???NSLog(@">>>tapit");?
    }

    ?

    ?

    ?

    ?

    翻页效果，类似下面的样子：

    

    在电子书应用中会很常见。这里需要两个要点：

    • 翻页动画
    • 手势上下轻扫（swipe）的处理

      ?

      先说一下轻扫（swipe）的实现，可以参考编写简单的手势示例：Tap了解手势种类。

      在viewDidLoad方法中注册了对上、下、左、右四个方向轻松的处理方法：

      - (void)viewDidLoad {?
      ????
      ???UISwipeGestureRecognizer *recognizer;?
      ????
      ??? recognizer =[[UISwipeGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleSwipeFrom:)];?
      ??? [recognizersetDirection:(UISwipeGestureRecognizerDirectionRight)];?
      ??? [[self view]addGestureRecognizer:recognizer];?
      ??? [recognizerrelease];?
      ????
      ??? recognizer =[[UISwipeGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleSwipeFrom:)];?
      ??? [recognizersetDirection:(UISwipeGestureRecognizerDirectionUp)];?
      ??? [[self view]addGestureRecognizer:recognizer];?
      ??? [recognizerrelease];?
      ????
      ??? recognizer =[[UISwipeGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleSwipeFrom:)];?
      ??? [recognizersetDirection:(UISwipeGestureRecognizerDirectionDown)];?
      ??? [[self view]addGestureRecognizer:recognizer];?
      ??? [recognizerrelease];?
      ????
      ??? recognizer =[[UISwipeGestureRecognizer alloc] initWithTarget:selfaction:@selector(handleSwipeFrom:)];?
      ??? [recognizersetDirection:(UISwipeGestureRecognizerDirectionLeft)];?
      ??? [[self view]addGestureRecognizer:recognizer];?
      ??? [recognizerrelease];?
      ????
      ????
      ??? [superviewDidLoad];

      ?

      可以看到，都是同一个方法，handleSwipeFrom。

      在该方法中，再识别具体是哪个方向的轻扫手势，比如判断是向下的轻扫：

      -(void)handleSwipeFrom:(UISwipeGestureRecognizer *)recognizer{?
      ???NSLog(@"Swipe received.");?
      ????
      ??? if(recognizer.direction==UISwipeGestureRecognizerDirectionDown){?
      ???????NSLog(@"swipe down");

      判断是向上的轻扫：

      if (recognizer.direction==UISwipeGestureRecognizerDirectionUp){?
      ???NSLog(@"swipe up");

      有关动画的处理，比如向下（往回）翻页，类似这样：

      [UIView beginAnimations:@"animationID"context:nil];?
      [UIView setAnimationDuration:0.7f];?
      [UIViewsetAnimationCurve:UIViewAnimationCurveEaseInOut];?
      [UIView setAnimationRepeatAutoreverses:NO];?
      [UIView setAnimationTransition:UIViewAnimationTransitionCurlDownforView:self.view cache:YES];

      [currentView removeFromSuperview];?
      [self.view addSubview:contentView];

      [UIView commitAnimations];

      向上（向前）翻页，只需改为：

      [UIView beginAnimations:@"animationID"context:nil];?
      [UIView setAnimationDuration:0.7f];?
      [UIViewsetAnimationCurve:UIViewAnimationCurveEaseInOut];?
      [UIView setAnimationRepeatAutoreverses:NO];?
      [UIViewsetAnimationTransition:UIViewAnimationTransitionCurlUp?forView:self.viewcache:YES];

      [currentView removeFromSuperview];?
      [self.view addSubview:contentView];

      [UIView commitAnimations];

      如果是电子书，还需要考虑一个问题，就是有多个页面（图形），比如50页。那么需要有一个数据结构来保存这些页面的图片路径：

      • objc数据结构，比如数组
      • sqlite数据库表

        这样，写一套翻页代码和加载什么图形之间就可以解耦。

        本文示例使用的是数组，类似这样：

        pages=[[NSArray alloc]initWithObjects:@"1.jpg",@"2.jpg",@"3.jpg",@"4.jpg",@"5.jpg",@"6.jpg",?
        ????????????????nil];

        图片保存在resources下。

        为了能让上页下页翻页的时候找到关联的页面，采用了如下机制：

        • 将图片封装为UIImageView显示
        • 可以为UIImageView设置一个tag值，值为数组下标+1
        • 这样，上级view有方法能根据tag查询到UIImageView，比如：UIView *currentView=[self.viewviewWithTag:currentTag];
        • 设置一个成员变量currentTag保存当前的tag值

          比如这样，当应用加载的时候显示第一页：

          ???currentTag=1;?
          ????
          ??? NSString*path = [[NSBundle mainBundle] pathForResource:@"pageflip1"ofType:@"mp3"];?
          ???player=[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURLfileURLWithPath:path] error:NULL];?
          ????
          ???//[[UIApplication sharedApplication] setStatusBarHidden:YESanimated:NO];?
          ???[[UIApplication sharedApplication] setStatusBarHidden:YESwithAnimation: UIStatusBarAnimationSlide];?
          ??? UIImageView*contentView = [[UIImageView alloc] initWithFrame:[[UIScreenmainScreen]applicationFrame]];??
          ??? [contentViewsetImage:[UIImage imageNamed:[pagesobjectAtIndex:(currentTag-1)]]];??
          ??? [contentViewsetUserInteractionEnabled:YES];?
          ???contentView.tag=currentTag;

          在翻页时的处理：

          if (currentTag<[pages count]){?
          ??? UIView*currentView=[self.viewviewWithTag:currentTag];?
          ???currentTag++;?
          ????
          ??? UIImageView*contentView = [[UIImageView alloc] initWithFrame:[[UIScreenmainScreen] applicationFrame]];?
          ??? [contentViewsetImage:[UIImage imageNamed:[pagesobjectAtIndex:(currentTag-1)]]];??
          ??? [contentViewsetUserInteractionEnabled:YES];?
          ???contentView.tag=currentTag;?
          ????
          ??? [UIViewbeginAnimations:@"animationID"context:nil];?
          ??? [UIViewsetAnimationDuration:0.7f];?
          ??? [UIViewsetAnimationCurve:UIViewAnimationCurveEaseInOut];?
          ??? [UIViewsetAnimationRepeatAutoreverses:NO];?
          ??? [UIViewsetAnimationTransition:UIViewAnimationTransitionCurlUpforView:self.view cache:YES];?
          ????
          ??? [currentViewremoveFromSuperview];?
          ??? [self.viewaddSubview:contentView];?
          ????
          ??? [UIViewcommitAnimations];