UIScrollView縮放使用Exc_Bad_Access崩潰應用程序

Question

當我嘗試滾動我的UIScrollView時，出現主要的Exc_Bad_Access錯誤。這個程序很簡單。我有一個UIViewController在AppDelegate中添加。然後，這是ViewController中的代碼。這工作正常滾動，但只要我加tmpScrollView.delegate = self。當我嘗試縮放時，該程序將不會滾動或縮放，並會給我出現Exc_Bad_Access錯誤。

@interface MainViewController : UIViewController &ltUIScrollViewDelegate> 
@property (nonatomic,retain) UIScrollView *tmpScrollView; 
@property (nonatomic,retain) UIView *containerView; 
@end 

- (void)viewDidLoad 
{ 
[super viewDidLoad]; 

// Do any additional setup after loading the view. 
tmpScrollView = [[UIScrollView alloc] initWithFrame:self.view.frame]; 
tmpScrollView.delegate = self; 
[self.view addSubview:tmpScrollView]; 

// Set up the container view to hold our custom view hierarchy 
CGSize containerSize = CGSizeMake(640.0f, 640.0f); 
self.containerView = [[UIView alloc] initWithFrame:(CGRect){.origin=CGPointMake(0.0f, 0.0f), .size=containerSize}]; 
[self.tmpScrollView addSubview:self.containerView]; 

// Set up custom view hierarchy 
UIView *redView = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 640.0f, 80.0f)]; 
redView.backgroundColor = [UIColor redColor]; 
[self.containerView addSubview:redView]; 

UIView *blueView = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 560.0f, 640.0f, 80.0f)]; 
blueView.backgroundColor = [UIColor blueColor]; 
[self.containerView addSubview:blueView]; 

UIView *greenView = [[UIView alloc] initWithFrame:CGRectMake(160.0f, 160.0f, 320.0f, 320.0f)]; 
greenView.backgroundColor = [UIColor greenColor]; 
[self.containerView addSubview:greenView]; 

UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"slow.png"]]; 
imageView.center = CGPointMake(320.0f, 320.0f); 
[self.containerView addSubview:imageView]; 

//Tell the scroll view the size of the contents 
self.tmpScrollView.contentSize = containerSize; 
} 

-(void)viewWillAppear:(BOOL)animated 
{ 
NSLog(@"Will Appear"); 
[super viewWillAppear:animated]; 

// Set up the minimum & maximum zoom scales 
CGRect scrollViewFrame = self.tmpScrollView.frame; 
CGFloat scaleWidth = scrollViewFrame.size.width/self.tmpScrollView.contentSize.width; 
CGFloat scaleHeight = scrollViewFrame.size.height/self.tmpScrollView.contentSize.height; 
CGFloat minScale = MIN(scaleWidth, scaleHeight); 

self.tmpScrollView.minimumZoomScale = minScale; 
self.tmpScrollView.maximumZoomScale = 1.0f; 
self.tmpScrollView.zoomScale = minScale; 

//***** Here is the line for setting the delegate 
self.tmpScrollView.delegate = self; 

[self centerScrollViewContents]; 
} 


-(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale 
{ 
NSLog(@"End Zoom"); 
} 

-(UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView { 
// Return the view that we want to zoom 
return self.containerView; 
} 

-(void)scrollViewDidZoom:(UIScrollView *)scrollView { 
// The scroll view has zoomed, so we need to re-center the contents 
[self centerScrollViewContents]; 
} 
@end 

感謝您的任何幫助。這已經快把我逼瘋了，現在一天...

編輯：添加centerScrollViewContens太：

- (void)centerScrollViewContents { 
    CGSize boundsSize = self.tmpScrollView.bounds.size; 
    CGRect contentsFrame = self.containerView.frame; 

    if (contentsFrame.size.width < boundsSize.width) { 
     contentsFrame.origin.x = (boundsSize.width - contentsFrame.size.width)/2.0f; 
    } else { 
     contentsFrame.origin.x = 0.0f; 
    } 

    if (contentsFrame.size.height < boundsSize.height) { 
     contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height)/2.0f; 
    } else { 
     contentsFrame.origin.y = 0.0f; 
    } 

    self.containerView.frame = contentsFrame; 
} 

Answer 1

任何代碼你提供工作對我end.May罰款是可能有某種問題在你的「centerScrollViewContents」方法中。你可以發佈這個方法的代碼嗎？

Answer 2

您需要計算滾動視圖的最小縮放比例。縮放比例爲1意味着內容以正常大小顯示。小於1的縮放比例顯示縮小的內容，而大於1的縮放比例顯示放大的內容。要獲得最小的縮放比例，您需要計算需要縮小的距離，以便圖像可以貼合地放入您的滾動視圖的邊界基於其寬度。然後，根據圖像的高度進行相同的操作。這兩個縮放比例的最小值將是滾動視圖的最小縮放比例。這給你一個縮放比例，你可以在完全縮小時看到整個圖像。

斯威夫特：

let scrollViewFrame = scrollView.frame 
let scaleWidth = scrollViewFrame.size.width/scrollView.contentSize.width 
let scaleHeight = scrollViewFrame.size.height/scrollView.contentSize.height 
let minScale = min(scaleWidth, scaleHeight); 
scrollView.minimumZoomScale = minScale; 

Objective-C的

CGFloat scrollViewFrame = scrollView.frame 
CGFloat scaleWidth = scrollViewFrame.size.width/scrollView.contentSize.width 
CGFloat scaleHeight = scrollViewFrame.size.height/scrollView.contentSize.height 
CGFloat minScale = min(scaleWidth, scaleHeight); 
scrollView.minimumZoomScale = minScale; 

從其他項目和個人經驗做在iOS重GPU（無盡的滾動，最大位圖大小，等等），我注意到每個設備都有自己的閾值。對於過去的項目，我也硬了下面的值作爲minimumZoomScale防止崩潰：

scale : 
     { 
       iPad : { 
        min : 0.8 
       , max : 1.6 
      } 
      , iPhone : { 
        min : 0.25 
       , max : 1.6 
      } 
      , iPhone6 : { 
        min : 0.3333 
       , max : 1.6 
      } 
      , iPhoneResizable: { 
        min : 1 
       , max : 1.6 
      } 
     } 

初學者偉大的教程：http://www.raywenderlich.com/76436/use-uiscrollview-scroll-zoom-content-swift