无法将图像加载到滚动视图中进行缩放和滚动

Question

我试图将图像加载到滚动视图中，并将图像添加到图像中，以便它可以放大和滚动。但不知何故，我无法让这个工作。我用xib文件构建了应用程序。起初我把scrollview放在xib文件的视图上，但是因为它没有解决（给我一个空白的黑屏），所以我试图把scrollview以编程方式放在.m文件中。但现在它给了我一个空白的白屏。我正在使用SDWebImage下载图像。这里是我的代码：

#import "ZoomAndPanViewController.h" 
#import "UIImageView+WebCache.h" 

@interface ZoomAndPanViewController() 
@property (nonatomic, strong) UIImageView *imageView; 
@property (nonatomic, strong) UIImage *image; 

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

@end 

@implementation ZoomAndPanViewController 

@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]; 
    // Do any additional setup after loading the view, typically from a nib. 
    CGRect scrollFrame = [[UIScreen mainScreen]applicationFrame]; 
    self.scrollView = [[UIScrollView alloc]initWithFrame:scrollFrame]; 
    self.scrollView.delegate = self; 

    // Set a nice title 
    self.title = @"Image"; 
    self.imageView = [[UIImageView alloc] init]; 
    self.image = [[UIImage alloc]init]; 
    __block UIActivityIndicatorView *activityIndicator; 
    [self.imageView setImageWithURL:[NSURL URLWithString:@"http://blablabla"] placeholderImage:nil options:SDWebImageProgressiveDownload progress:^(NSUInteger receivedSize, long long expectedSize) 
    { 
     if (!activityIndicator) 
     { 
      NSLog(@"setting up the indicator"); 
      [self.imageView addSubview:activityIndicator = [UIActivityIndicatorView.alloc initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray]]; 
      activityIndicator.center = self.imageView.center; 
      [activityIndicator startAnimating]; 
      NSLog(@"indicator start animating"); 
     } 
    } 
          completed:^(UIImage *uiimage, NSError *error, SDImageCacheType cacheType) 
    { 
     NSLog(@"download image completed"); 
     [activityIndicator removeFromSuperview]; 
     activityIndicator = nil; 
     self.image = uiimage; 
     [self.imageView setImage:self.image]; 
     NSLog(@"image vs uiimage : %f x %f vs %f vs %f", self.image.size.width, self.image.size.height, uiimage.size.width, uiimage.size.height); 
    }]; 

    // Set up the image we want to scroll & zoom and add it to the scroll view 


    self.imageView.frame = (CGRect){.origin=CGPointMake(0.0f, 0.0f), .size=self.image.size}; 
    [self.scrollView addSubview:self.imageView]; 

    // Tell the scroll view the size of the contents 
    self.scrollView.contentSize = self.image.size; 
    NSLog(@"scrollview contentsize %f x %f", self.image.size.width, self.scrollView.contentSize.height); 
    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]; 
    //[self.view addSubview:self.scrollView]; 
    [SDWebImageManager.sharedManager.imageDownloader setValue:@"SDWebImage Demo" forHTTPHeaderField:@"AppName"]; 
    SDWebImageManager.sharedManager.imageDownloader.queueMode = SDWebImageDownloaderLIFOQueueMode; 

} 

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

- (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)didReceiveMemoryWarning 
{ 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 

- (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 

任何线索我做错了什么我的代码和任何帮助将不胜感激。

谢谢！

Answer 1

只需创建2类名为CustomScroll.h和.M

在CustomScroll.h写

@interface CustomScroll : UIScrollView 
{ 

} 

@property (nonatomic,strong) IBOutlet UIView *imageContainer; 

而且在.M写代码如下：

@synthesize imageContainer; 

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
{ 

//self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
    if (self) { 
     // Custom initialization 
    } 
    return self; 

} 

// Override layoutSubviews to center content 

- (void)layoutSubviews 
{ 

    [super layoutSubviews]; 

    // center the image as it becomes smaller than the size of the screen 

    CGSize boundsSize = self.bounds.size; 

    CGRect frameToCenter = imageContainer.frame; 

    // center horizontally 
    if (frameToCenter.size.width < boundsSize.width) 
     frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width)/2; 
    else 
     frameToCenter.origin.x = 0; 

    // center vertically 
    if (frameToCenter.size.height < boundsSize.height) 
     frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height)/2; 
    else 
     frameToCenter.origin.y = 0; 

    imageContainer.frame = frameToCenter; 

    NSLog(@"imageContainer.frame.height=== %f",imageContainer.frame.size.height); 

} 

-(BOOL)shouldAutorotateToInterfaceOrientation:UIInterfaceOrientation)interfaceOrientation 
{ 

    // Return YES for supported orientations 
    return (interfaceOrientation == UIInterfaceOrientationPortrait); 

} 

，并在类你要在.h文件中导入图像的位置导入CustomScroll.h并使对象像

CustomScroll *customScrl; 

并在您的视图中使用ScrollView并将imageview放入其中并将scrollview与customScrl绑定（不要忘记绑定委托并在.h文件中添加UIScrollViewDelegate）并在自定义类选项卡中将CustomScroll编写为类。

现在.m文件写入时要显示的图像或在viewDidLoad中：

// Zoom image inside Scrol view // 
// outputImage is my imageview inside Scrollview 
    self.customScrl.contentSize= CGSizeMake(outputImage.frame.size.width, outputImage.frame.size.height); 
    self.customScrl.maximumZoomScale=5.0; 
    self.customScrl.minimumZoomScale=1.0; 
    self.customScrl.clipsToBounds=YES; 
    self.customScrl.delegate=self; 
    [self.customScrl addSubview:outputImage]; 
    self.customScrl.imageContainer=outputImage; 

    [self.view addSubview:customScrl]; 


#pragma ImageZooming Function 

-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView 
{ 
    UIImageView *zoomImg = outputImage; 
    //NSLog(@"zoom img=== %@",zoomImg); 

    return zoomImg; 
} 

只是做书面。它一定会为你工作。 :)