如何將自動滾動功能添加到iphone sdk中的視圖？

Question

我是新來的自動滾動功能。我有一個很長的.png文件。我想要做的是，當我點擊一個按鈕時，我想自動開始滾動該圖像。我已經通過sdk中的scrollView示例代碼。但我感到困惑。請任何一個幫助我提前

感謝 Praveena

Answer 1

滾動通過設置內容偏移來實現的。

想象構建這樣的一個視圖控制器（在-viewDidLoad如）：

// Load image. 
UIImage *image = [UIImage imageNamed:@"image.png"]; 

// Create image view to hold the image. 
imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, [image size].width, [image size].height)]; 

[imageView setImage:image]; 

// Create a scroll view that is the size of the view. 
scrollView = [[UIScrollView alloc] initWithFrame:[[self view] bounds]]; 

// Important: If the content size is less than the scroll view frame, then it will not scroll. 
[scrollView setContentSize:[image size]]; 

// Add to view hierarchy. 
[scrollView addSubview:imageView]; 
[[self view] addSubview:scrollView]; 

爲了使其滾動，只是這樣做：

[scrollView setContentOffset:CGPointMake(0, 100) animated:YES]; 

要使滾動是連續的，您需要設置一個更新內容偏移的計時器。

Answer 2

- (void) scrollView 
{ 
    CGFloat currentOffset = scrollImage.contentOffset.x; 

    CGFloat newOffset; 

    if(currentOffset == 3840) 
    { 
     currentOffset = -320.0; 

     [scrollImage setContentOffset:CGPointMake(newOffset,0.0) animated:NO]; 
    } 

    newOffset = currentOffset + 320; 

     [UIScrollView beginAnimations:nil context:NULL]; 
     [UIScrollView setAnimationDuration:2.1]; 
     [scrollImage setContentOffset:CGPointMake(newOffset,0.0)]; 
     [UIScrollView commitAnimations]; 
}