http://marshal.easymorse.com/archives/3760
翻頁效果,類似下面的樣子:
在電子書應用中會很常見。這里需要兩個要點:
- 翻頁動畫
- 手勢上下輕掃(swipe)的處理
先說一下輕掃(swipe)的實現,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];
可以看到,都是同一個方法,handleSwipeFrom。
在該方法中,再識別具體是哪個方向的輕掃手勢,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");
有關動畫的處理,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,還需要考慮一個問題,就是有多個頁面(圖形),比如50頁。那么需要有一個數據結構來保存這些頁面的圖片路徑:
- objc數據結構,比如數組
- sqlite數據庫表
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候找到關聯的頁面,采用了如下機制:
- 將圖片封裝為UIImageView顯示
- 可以為UIImageView設置一個tag值,值為數組下標+1
- 這樣,上級view有方法能根據tag查詢到UIImageView,比如:UIView *currentView=[self.view viewWithTag:currentTag];
- 設置一個成員變量currentTag保存當前的tag值
比如這樣,當應用加載的時候顯示第一頁:
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];
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