IOS ScrollView問題

Question

嘿，我正在關注這個tutorial，目前正在進行第一步，但我正在經歷一些奇怪的行爲。本教程旨在爲圖像創建滾動視圖，並以展示如何使用頁面控制器創建分頁的水平ScrollView結束。我跟着第一部分，事情似乎工作正常。然而，當我運行代碼時，它沒有正確執行，經過大約一個小時的調試後，我下載了最終的項目，在手機上運行它以檢查它是否正常工作（它是），然後將代碼複製到我所需的文件中項目。我的項目仍然無法運行。所以我認爲這一定是我的故事板在項目設置中配置的方式。然後我打開了這個工作示例，清除了他們的故事板，並創建了視圖，並以我完成的項目中完成的方式和順序創建了我的自我。巴姆！它仍然有效，當我刪除故事板中的所有視圖並以完全相同的方式重新創建它們時，仍然沒有任何結果。有人能看看這個教程，並告訴我，如果我瘋了，或者他們遇到類似的結果。我將其縮小爲兩種可能性，本教程末尾提供的項目創建方式不同，代表或插座以僅與該項目協同工作的方式聯結，或者該項目使用早期版本的iPhone開發工具包可與當前版本的XCode配合使用，但不能在創建新項目時使用。然後我再次相當新，所以我會拋出我使用的代碼並希望最好。

ViewController.h文件：

#import <UIKit/UIKit.h> 

@interface ViewController : UIViewController <UIScrollViewDelegate> 

@property (nonatomic, strong) IBOutlet UIScrollView *scrollView; 

@end 

ViewController.m文件：

#import "ViewController.h" 

@interface ViewController() 
@property (nonatomic, strong) UIImageView *imageView; 

- (void)centerScrollViewContents; 
- (void)scrollViewDoubleTapped:(UITapGestureRecognizer*)recognizer; 
- (void)scrollViewTwoFingerTapped:(UITapGestureRecognizer*)recognizer; 
@end 

@implementation ViewController 

@synthesize scrollView = _scrollView; 

@synthesize imageView = _imageView; 

- (void)centerScrollViewContents { 
    CGSize boundsSize = self.scrollView.bounds.size; 
    CGRect contentsFrame = self.imageView.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.imageView.frame = contentsFrame; 
} 

- (void)scrollViewDoubleTapped:(UITapGestureRecognizer*)recognizer { 
    // Get the location within the image view where we tapped 
    CGPoint pointInView = [recognizer locationInView:self.imageView]; 

    // Get a zoom scale that's zoomed in slightly, capped at the maximum zoom scale specified by the scroll view 
    CGFloat newZoomScale = self.scrollView.zoomScale * 1.5f; 
    newZoomScale = MIN(newZoomScale, self.scrollView.maximumZoomScale); 

    // Figure out the rect we want to zoom to, then zoom to it 
    CGSize scrollViewSize = self.scrollView.bounds.size; 

    CGFloat w = scrollViewSize.width/newZoomScale; 
    CGFloat h = scrollViewSize.height/newZoomScale; 
    CGFloat x = pointInView.x - (w/2.0f); 
    CGFloat y = pointInView.y - (h/2.0f); 

    CGRect rectToZoomTo = CGRectMake(x, y, w, h); 

    [self.scrollView zoomToRect:rectToZoomTo animated:YES]; 
} 

- (void)scrollViewTwoFingerTapped:(UITapGestureRecognizer*)recognizer { 
    // Zoom out slightly, capping at the minimum zoom scale specified by the scroll view 
    CGFloat newZoomScale = self.scrollView.zoomScale/1.5f; 
    newZoomScale = MAX(newZoomScale, self.scrollView.minimumZoomScale); 
    [self.scrollView setZoomScale:newZoomScale animated:YES]; 
} 

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    // Set a nice title 
    self.title = @"Image"; 

    // Set up the image we want to scroll & zoom and add it to the scroll view 
    UIImage *image = [UIImage imageNamed:@"photo1.png"]; 
    self.imageView = [[UIImageView alloc] initWithImage:image]; 
    self.imageView.frame = (CGRect){.origin=CGPointMake(0.0f, 0.0f), .size=image.size}; 
    [self.scrollView addSubview:self.imageView]; 

    // Tell the scroll view the size of the contents 
    self.scrollView.contentSize = image.size; 

    UITapGestureRecognizer *doubleTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(scrollViewDoubleTapped:)]; 
    doubleTapRecognizer.numberOfTapsRequired = 2; 
    doubleTapRecognizer.numberOfTouchesRequired = 1; 
    [self.scrollView addGestureRecognizer:doubleTapRecognizer]; 

    UITapGestureRecognizer *twoFingerTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(scrollViewTwoFingerTapped:)]; 
    twoFingerTapRecognizer.numberOfTapsRequired = 1; 
    twoFingerTapRecognizer.numberOfTouchesRequired = 2; 
    [self.scrollView addGestureRecognizer:twoFingerTapRecognizer]; 
} 

- (void)viewWillAppear:(BOOL)animated { 
    [super viewWillAppear:animated]; 

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

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

    [self centerScrollViewContents]; 
} 

- (void)viewDidUnload 
{ 
    [super viewDidUnload]; 
    // Release any retained subviews of the main view. 
} 

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation 
{ 
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown); 
} 

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

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

@end 

，因爲它在教程項目做上面的代碼不起作用。下面的UIScrollView的委託方法viewForZoomingInScrollView產生這個錯誤：

2013-05-14 10:01:18.585 TestScrollView[3809:907] Made it

May 14 10:01:18 Scott-Laroses-iPhone TestScrollView[3809] : CGAffineTransformInvert: singular matrix.

May 14 10:01:18 Scott-Laroses-iPhone TestScrollView[3809] : CGAffineTransformInvert: singular matrix.

這讓我想起了啦免費統計沒有正確設置，儘管我這樣做完全一樣的教程和程序時沒有工作。有任何想法嗎？

Answer 1

我想通了！問題在於自動佈局約束混亂了屏幕視圖。所以我禁用了自動佈局，它工作正常。

Answer 2

如果賦值爲0，那麼您的問題可能來自zoomScale和minimumZoomScale。確保這兩個屬性的值從不爲0。