tap是指輕觸手勢。類似鼠標(biāo)操作的點(diǎn)擊。從iOS 3.2版本開始支持完善的手勢api：

• tap：輕觸
• long press：在一點(diǎn)上長按
• pinch：兩個(gè)指頭捏或者放的操作
• pan：手指的拖動(dòng)
• swipe：手指在屏幕上很快的滑動(dòng)
• rotation：手指反向操作

這為開發(fā)者編寫手勢識別操作，提供了很大的方便，想想之前用android寫手勢滑動(dòng)的代碼（ 編寫android簡單的手勢切換視圖示例 ），尤其感到幸福。

這里寫一個(gè)簡單的tap操作。在下面視圖的藍(lán)色視圖內(nèi)增加對tap的識別：

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當(dāng)用手指tap藍(lán)色視圖的時(shí)候，打印日志輸出：

代碼很簡單，首先要聲明tap的recognizer：

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

在這里：

• initWithTarget:self，要引用到Controller，因?yàn)橐话氵@部分代碼寫在controller中，用self；
• action:@selector(handleTapFrom:)，賦值一個(gè)方法名，用于當(dāng)手勢事件發(fā)生后的回調(diào)；
• [infoView addGestureRecognizer:recognizer]，為view注冊這個(gè)手勢識別對象，這樣當(dāng)手指在該視圖區(qū)域內(nèi)，可引發(fā)手勢，之外則不會(huì)引發(fā)

對應(yīng)的回調(diào)方法：

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

controller相關(guān)方法完整的代碼（包含了一些與本文無關(guān)的視圖構(gòu)建代碼）：

// Implement loadView to create a view hierarchy programmatically, without using a nib.
- (void)loadView {
??? //去掉最頂端的狀態(tài)攔
??? [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation: UIStatusBarAnimationSlide];
???
??? UIImage *image=[UIImage imageNamed:@"3.jpg"];
???
??? //創(chuàng)建背景視圖
??? self.view=[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
??? UIImageView *backgroudView=[[UIImageView alloc] initWithImage:image];
??? [self.view addSubview:backgroudView];
???
??? /*
??? UIToolbar *toolBar=[[UIToolbar alloc] initWithFrame:CGRectMake(0, 1024-70, 768, 70)];
??? toolBar.alpha=0.8;
??? toolBar.tintColor = [UIColor colorWithRed:.3 green:.5 blue:.6 alpha:.1];
???
??? NSArray *items=[NSArray arrayWithObjects:[[UIBarButtonItem alloc] initWithTitle:@"test" style:UIBarButtonItemStyleDone target:self action:nil],nil];
??? toolBar.items=items;
??? [self.view addSubview:toolBar];
??? */
???
??? UIView *bottomView=[[UIView alloc]? initWithFrame:CGRectMake(0, 1024-70, 768, 70)];
??? bottomView.backgroundColor=[UIColor grayColor];
??? bottomView.alpha=0.8;
???
??? //UIButton *backButton=[[UIButton alloc] initWithFrame:CGRectMake(10, 10, 100, 40)];
??? UIButton *backButton=[UIButton buttonWithType: UIButtonTypeRoundedRect];
??? [backButton setTitle:@"ok" forState:UIControlStateNormal];
??? backButton.frame=CGRectMake(10, 15, 100, 40);
???
??? [bottomView addSubview:backButton];
???
??? [self.view addSubview:bottomView];
???
??? UIView *infoView=[[UIView alloc] initWithFrame:CGRectMake(200, 700, 768-400, 70)];
??? infoView.backgroundColor=[UIColor blueColor];
??? infoView.alpha=0.6;
??? infoView.layer.cornerRadius=6;
??? infoView.layer.masksToBounds=YES;
??? [self.view addSubview:infoView];
???
??? UITapGestureRecognizer *recognizer=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapFrom:)];
??? [infoView addGestureRecognizer:recognizer];
??? [recognizer release];
}

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

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翻頁效果，類似下面的樣子：

在電子書應(yīng)用中會(huì)很常見。這里需要兩個(gè)要點(diǎn)：

• 翻頁動(dòng)畫
• 手勢上下輕掃（swipe）的處理

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先說一下輕掃（swipe）的實(shí)現(xiàn)，可以參考 編寫簡單的手勢示例：Tap 了解手勢種類。

在viewDidLoad方法中注冊了對上、下、左、右四個(gè)方向輕松的處理方法：

- (void)viewDidLoad {
???
??? UISwipeGestureRecognizer *recognizer;
???
??? recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
??? [recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
??? [[self view] addGestureRecognizer:recognizer];
??? [recognizer release];
???
??? recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
??? [recognizer setDirection:(UISwipeGestureRecognizerDirectionUp)];
??? [[self view] addGestureRecognizer:recognizer];
??? [recognizer release];
???
??? recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
??? [recognizer setDirection:(UISwipeGestureRecognizerDirectionDown)];
??? [[self view] addGestureRecognizer:recognizer];
??? [recognizer release];
???
??? recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
??? [recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
??? [[self view] addGestureRecognizer:recognizer];
??? [recognizer release];
???
???
??? [super viewDidLoad];

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可以看到，都是同一個(gè)方法，handleSwipeFrom。

在該方法中，再識別具體是哪個(gè)方向的輕掃手勢，比如判斷是向下的輕掃：

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

判斷是向上的輕掃：

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

有關(guān)動(dòng)畫的處理，比如向下（往回）翻頁，類似這樣：

[UIView beginAnimations:@"animationID" context:nil];
[UIView setAnimationDuration:0.7f];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
[UIView setAnimationRepeatAutoreverses:NO];
[UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES];

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

[UIView commitAnimations];

向上（向前）翻頁，只需改為：

[UIView beginAnimations:@"animationID" context:nil];
[UIView setAnimationDuration:0.7f];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
[UIView setAnimationRepeatAutoreverses:NO];
[UIView setAnimationTransition: UIViewAnimationTransitionCurlUp forView:self.view cache:YES];

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

[UIView commitAnimations];

如果是電子書，還需要考慮一個(gè)問題，就是有多個(gè)頁面（圖形），比如50頁。那么需要有一個(gè)數(shù)據(jù)結(jié)構(gòu)來保存這些頁面的圖片路徑：

• objc數(shù)據(jù)結(jié)構(gòu)，比如數(shù)組
• sqlite數(shù)據(jù)庫表

這樣，寫一套翻頁代碼和加載什么圖形之間就可以解耦。

本文示例使用的是數(shù)組，類似這樣：

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

圖片保存在resources下。

為了能讓上頁下頁翻頁的時(shí)候找到關(guān)聯(lián)的頁面，采用了如下機(jī)制：

• 將圖片封裝為UIImageView顯示
• 可以為UIImageView設(shè)置一個(gè)tag值，值為數(shù)組下標(biāo)+1
• 這樣，上級view有方法能根據(jù)tag查詢到UIImageView，比如：UIView *currentView=[self.view viewWithTag:currentTag];
• 設(shè)置一個(gè)成員變量currentTag保存當(dāng)前的tag值

比如這樣，當(dāng)應(yīng)用加載的時(shí)候顯示第一頁：

??? currentTag=1;
???
??? NSString *path = [[NSBundle mainBundle] pathForResource:@"pageflip1" ofType:@"mp3"];
??? player=[[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL];
???
??? //[[UIApplication sharedApplication] setStatusBarHidden:YES animated:NO];
??? [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation: UIStatusBarAnimationSlide];
??? UIImageView *contentView = [[UIImageView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];?
??? [contentView setImage:[UIImage imageNamed:[pages objectAtIndex:(currentTag-1)]]];?
??? [contentView setUserInteractionEnabled:YES];
??? contentView.tag=currentTag;

在翻頁時(shí)的處理：

if (currentTag<[pages count]) {
??? UIView *currentView=[self.view viewWithTag:currentTag];
??? currentTag++;
???
??? UIImageView *contentView = [[UIImageView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
??? [contentView setImage:[UIImage imageNamed:[pages objectAtIndex:(currentTag-1)]]];?
??? [contentView setUserInteractionEnabled:YES];
??? contentView.tag=currentTag;
???
??? [UIView beginAnimations:@"animationID" context:nil];
??? [UIView setAnimationDuration:0.7f];
??? [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
??? [UIView setAnimationRepeatAutoreverses:NO];
??? [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:self.view cache:YES];
???
??? [currentView removeFromSuperview];
??? [self.view addSubview:contentView];
???
??? [UIView commitAnimations];

UISwipeGestureRecognizer ---手指動(dòng)作