在UIScrollView中縮放UIImageView的行爲奇怪

Question

我有以下問題，夥計們。我有一個非常像Apple的PhotoScroller的應用程序。我想通過滑動屏幕從圖像跳轉到圖像。我可以做到這一點，但我無法放大圖像。這是問題 - 我有一個圖像陣列。如果數組內只有一個對象，則縮放沒有問題。但是如果陣列中有更多圖像，當我嘗試縮放時，它們的行爲會很奇怪。圖像沒有被縮放，並且它在所需的位置離開屏幕。這裏是我的代碼：

int pageWidth = 1024; 
int pageHeight = 768; 
int counter = 0; 

self.view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, pageWidth, pageHeight)]; 

CGRect containerFrame = self.view.frame; 
scrollView = [[UIScrollView alloc] initWithFrame:containerFrame]; 
[self.view addSubview:scrollView]; 

NSMutableArray *all = [[NSMutableArray alloc] init]; 
[all addObject:[UIImage imageNamed:@"222.jpg"]]; 

CGSize scrollSize = CGSizeMake(pageWidth * [all count], pageHeight); 
[scrollView setContentSize:scrollSize]; 



for (UIImage *image in all) 
{ 
    UIImage *pageImage = [[UIImage alloc] init]; 
    pageImage = [all objectAtIndex:counter]; 

    CGRect scrollFrame = CGRectMake(pageWidth * counter, 0, pageWidth, pageHeight); 
    miniScrollView = [[UIScrollView alloc] initWithFrame:scrollFrame]; 
    [scrollView addSubview:miniScrollView]; 

    CGSize miniScrollSize = CGSizeMake(pageImage.size.width, pageImage.size.height); 
    [miniScrollView setContentSize:miniScrollSize]; 

    UIImageView *tempImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, pageImage.size.width, pageImage.size.height)]; 
    tempImageView.image = [all objectAtIndex:counter]; 
    self.imageView = tempImageView; 

    miniScrollView.maximumZoomScale = 3.0; 
    miniScrollView.minimumZoomScale = 1.0; 
    miniScrollView.clipsToBounds = YES; 
    miniScrollView.delegate = self; 
    miniScrollView.showsHorizontalScrollIndicator = NO; 
    miniScrollView.showsVerticalScrollIndicator = NO; 
    miniScrollView.bouncesZoom = YES; 
    [miniScrollView addSubview:imageView]; 

    counter ++; 
} 
[scrollView setPagingEnabled:YES]; 
[scrollView setScrollEnabled:YES]; 
} 


-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView 
{ 
    return imageView; 
} 

你有什麼想法是什麼錯？因爲我正在嘗試近2周的時間完成這項工作。

Answer 1

我也參與過這類應用。您可以做的第一件事是獲取ScrollView的一個單獨的子類，以便可以輕鬆處理所有分頁和縮放操作。在你的scrollView類中，你可以參考下面的代碼片段。

@interface PhotoScrollView : UIScrollView<UIScrollViewDelegate,UIGestureRecognizerDelegate> 
{ 
int finalPhotoWidth; 
int finalPhotoHeight; 
} 


// to contain image 
@property (strong, nonatomic) UIImageView *imageView; 

- (id)initWithFrame:(CGRect)frame andImage:(UIImage *)photo 
{ 
    self = [super initWithFrame:frame]; 
    if (self) 
    { 
    // Initialization code 

    [self initializeScrollViewWithImage:photo]; 

    //setting gesture recognizer for single tap 
    UITapGestureRecognizer *singleTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(scrollViewSingleTapped:)]; 
    singleTapRecognizer.delegate = self; 
    singleTapRecognizer.numberOfTapsRequired = 1; 
    [self addGestureRecognizer:singleTapRecognizer]; 


    //setting gesture recognizer for Double tap 
    UITapGestureRecognizer *doubleTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(scrollViewDoubleTapped:)]; 
    doubleTapRecognizer.delegate = self; 
    doubleTapRecognizer.numberOfTapsRequired = 2; 

    [self addGestureRecognizer:doubleTapRecognizer]; 
    [singleTapRecognizer requireGestureRecognizerToFail:doubleTapRecognizer]; 

    singleTapActivated = FALSE; 

    self.backgroundColor = [UIColor blackColor]; 

    self.minimumZoomScale = 1.0f; 
    self.maximumZoomScale = 15.0f; 
    self.zoomScale = 1.0f; 

    self.delegate = self; 
} 
return self; 
} 


//for sizing the frame by giving height and width 
-(void)initializeScrollViewWithImage:(UIImage*)photo 
{ 

finalPhotoWidth = photo.size.width; 
finalPhotoHeight = photo.size.height; 

//Pre-checking of frame and setting the height and width accordingly 

if (finalPhotoHeight > self.frame.size.height) 
{ 
    // if photo height is bigger than frame height, re-adjust the photo height and width accordingly 

    finalPhotoHeight = self.frame.size.height; 
    finalPhotoWidth = (photo.size.width/photo.size.height) * finalPhotoHeight; 
} 
if (finalPhotoWidth > self.frame.size.width) 
{ 
    // if photo width is bigger than frame width, re-adjust the photo height and width accordingly 

    finalPhotoWidth = self.frame.size.width; 
    finalPhotoHeight = (photo.size.height/photo.size.width) * finalPhotoWidth; 
} 
    if (finalPhotoHeight < self.frame.size.height && finalPhotoWidth < self.frame.size.width) 
    { 
    // if the photo is smaller than frame, increase the photo width and height accordingly 

    finalPhotoWidth = self.frame.size.width; 
    finalPhotoHeight = self.frame.size.height; 
    } 

    //initialising imageView with the thumbnail photo 

    self.imageView = [[UIImageView alloc] initWithImage:photo]; 
    self.imageView.contentMode = UIViewContentModeScaleAspectFit; 

    //setting frame according to the modified width and height 
    if(!isnan(finalPhotoWidth) && !isnan(finalPhotoHeight)) 
    { 
    self.imageView.frame = CGRectMake((self.frame.size.width - finalPhotoWidth)/2, (self.frame.size.height - finalPhotoHeight)/2, finalPhotoWidth, finalPhotoHeight); 

    } 

    // setting scrollView properties 

    self.contentSize = self.imageView.frame.size; 

    // add image view to scroll view 
    [self addSubview:self.imageView]; 
} 

//to deny the simultaneous working of single and double taps 
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer 
{ 

return NO; 
} 

// Gesture handleer for single tap gesture 
-(void)scrollViewSingleTapped:(UITapGestureRecognizer *)recognizer 
{ 
if(!singleTapActivated) 
{ 
//do as per requirement 
     singleTapActivated = TRUE; 
} 

else 
{ 
    //do as per requirement 
    singleTapActivated = FALSE; 
} 
} 


//for zooming after double tapping 
- (void)scrollViewDoubleTapped:(UITapGestureRecognizer*)recognizer 
{ 

//to check whether image is zoomed 
if (self.zoomScale != 1.0f) 
{ 
    //if image is zoomed, then zoom out 


    [self setZoomScale:1.0 animated:YES]; 
    self.imageView.frame = CGRectMake((self.frame.size.width - finalPhotoWidth)/2, (self.frame.size.height - finalPhotoHeight)/2, finalPhotoWidth, finalPhotoHeight); 

    [self.observer photoZoomStopped]; 

} 
else 
{ 

    // get the point of image which is double 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.zoomScale * 4.0f; 
    newZoomScale = MIN(newZoomScale, self.maximumZoomScale); 

    // Figure out the rect we want to zoom to, then zoom to it 

    CGSize scrollViewSize = self.imageView.frame.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 zoomToRect:rectToZoomTo animated:YES]; 
} 

} 

// To re-center the image after zooming in and zooming out 
- (void)centerScrollViewContents 
{ 
CGSize boundsSize = self.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; 
} 

//for zooming in and zooming out 
- (void)scrollViewDidZoom:(UIScrollView *)scrollView 
{ 
if (self.zoomScale > 1.0f) 
{ 
    [self.observer photoZoomStarted]; 

    [self centerScrollViewContents]; 
} 
else 
{ 
    self.bouncesZoom = NO; 

    [self.observer photoZoomStopped]; 

     // for zooming out by pinching 
    [self centerScrollViewContents]; 
} 

// The scroll view has zoomed, so we need to re-center the contents 
} 

- (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView 
{ 
return self.imageView; 
} 

請讓我知道它是否有幫助。謝謝:)