添加在幻燈片過渡效果

Question

我想一個過渡效果添加到我的幻燈片：這裏是我的代碼

- (void)viewDidLoad 
{ 
[super viewDidLoad]; 
photos = [[NSMutableArray alloc] init]; 

NSXMLParser *photoParser = [[NSXMLParser alloc] initWithContentsOfURL:[NSURL 
URLWithString:@"http://localhost/index.xml"]]; 
[photoParser setDelegate:(id)self]; 
[photoParser parse]; 

currentImage = 0; 

NSURL *imageURL = [NSURL URLWithString:[photos objectAtIndex:0]]; 
NSData *imageData = [NSData dataWithContentsOfURL:imageURL]; 
[imgView setImage:[UIImage imageWithData:imageData]]; 

timer = [NSTimer scheduledTimerWithTimeInterval: 0.5 
             target: self 
             selector: @selector(handleTimer:) 
             userInfo: nil 
             repeats: YES]; 
} 

- (void) handleTimer: (NSTimer *) timer { 
currentImage++; 
if (currentImage >= photos.count) 
    currentImage = 0; 

NSURL *imageURL = [NSURL URLWithString:[photos objectAtIndex:currentImage]]; 
NSData *imageData = [NSData dataWithContentsOfURL:imageURL]; 
[imgView setImage:[UIImage imageWithData:imageData]]; 
} 

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName 
namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName 
attributes:(NSDictionary *)attributeDict { 
if ([elementName isEqualToString:@"photo"]) { 
    [photos addObject:[attributeDict objectForKey:@"url"]]; 
} 
} 

我想我應該用

[UIView transitionFromView:currentView toView:nextView duration:1.0 
options:UIViewAnimationOptionTransitionCrossDissolve completion:nil]; 

，但我也不怎麼以填充transitionFRomView：和toView：字段。我只有一個視圖

感謝您的幫助

Answer 1

您可以使用該方法transitionWithView:duration:options:animations:completion:爲其documentation說：

您可以使用此模塊來添加，刪除，顯示或隱藏子視圖的指定視圖。

這是你如何使用這個方法的例子：

- (void) handleTimer: (NSTimer *) timer { 
    currentImage++; 
    if (currentImage >= photos.count) currentImage = 0; 

    NSURL *imageURL = [NSURL URLWithString:[photos objectAtIndex:currentImage]]; 
    NSData *imageData = [NSData dataWithContentsOfURL:imageURL] 
    [UIView transitionWithView:containerView 
     duration:2 
     options:UIViewAnimationOptionTransitionFlipFromLeft 
     animations:^{ 
      [imgView removeFromSuperview]; 
      imgView = // create a new image view 
      [imgView setImage:[UIImage imageWithData:imageData]]; 
      [containerView addSubview:toView]; 
     } completion:NULL]; 
} 

凡containerView是imgView父視圖，最有可能是self.view。