無法放大/縮小webView中的子類的scrollView

Question

我有一個類是webView的子類。當webView的scrollview被縮放或滾動時，我需要做一些計算。加載在webView中的內容是pdf文件。在iOS 5中我得到滾動視圖有：

[super scrollView] 

，並在iOS 4的：

for (id subview in webView.subviews) 
    if ([[subview class] isSubclassOfClass: [UIScrollView class]]) 
    return subview; 

它的正常工作與iOS 5，但在iOS 4的時候我改變滾動視圖的委託我再也不能放大進/出webView。

任何想法如何更改該scrollView的委託？

Answer 1

我實現了這樣的事情：

@interface ProxyScrollView : NSObject <UIScrollViewDelegate> 
{ 
    UIScrollView* _view; 
    id<UIScrollViewDelegate> origDelegate; 
    id<UIScrollViewDelegate> newDelegate; 
} 

+ (ProxyScrollView*) proxyScrollViewWithScrollView: (UIScrollView*) scrollView; 

@end 

@implementation ProxyScrollView 

- (id) initWithScrollView: (UIScrollView*) scrollView 
{ 
    if(self != nil) 
    { 
     _view = scrollView; 
     origDelegate = _view.delegate; 
     [_view setDelegate:self]; 
     newDelegate = nil; 
     [_view retain]; 

     return self; 
    } 

    return nil; 
} 

-(void)dealloc 
{ 
    _view.delegate = origDelegate; 
    [_view release]; 
    _view = nil; 
    origDelegate = nil; 
    newDelegate = nil; 
} 

+ (ProxyScrollView*) proxyScrollViewWithScrollView: (UIScrollView*) scrollView 
{ 
    ProxyScrollView* retVal = [[[ProxyScrollView alloc] initWithScrollView:scrollView] autorelease]; 

    return retVal; 
} 

- (BOOL)isKindOfClass:(Class)aClass 
{ 
    return [_view isKindOfClass:aClass]; 
} 

- (BOOL)isMemberOfClass:(Class)aClass 
{ 
    return [_view isMemberOfClass:aClass]; 
} 

- (BOOL)respondsToSelector:(SEL)aSelector 
{ 
    if ([super respondsToSelector:aSelector]) 
     return YES; 
    else { 
     /* Here, test whether the aSelector message can  * 
     * be forwarded to another object and whether that * 
     * object can respond to it. Return YES if it can. */ 
     if([_view respondsToSelector:aSelector]) 
      return YES; 
    } 
    return NO; 
} 

- (NSMethodSignature *)methodSignatureForSelector:(SEL)sel 
{ 
    NSMethodSignature *sig = [super methodSignatureForSelector:sel]; 

    if(!sig) 
    { 
     sig = [_view methodSignatureForSelector:sel]; 
    } 

    return sig; 
} 

- (void)forwardInvocation:(NSInvocation *)inv 
{ 
    NSLog(@"inv.selector: %@", NSStringFromSelector(inv.selector)); 

    if([_view respondsToSelector: inv.selector]) 
    { 
     [inv invokeWithTarget: _view]; 
    } 
} 

- (void)setDelegate:(id<UIScrollViewDelegate>)delegate 
{ 
    newDelegate = delegate; 
} 


- (void)scrollViewDidScroll:(UIScrollView *)scrollView 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate performSelector:_cmd withObject:scrollView]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate performSelector:_cmd withObject:scrollView]; 
} 

- (void)scrollViewDidZoom:(UIScrollView *)scrollView 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate performSelector:_cmd withObject:scrollView]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate performSelector:_cmd withObject:scrollView]; 
} 

-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate performSelector:_cmd withObject:scrollView]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate performSelector:_cmd withObject:scrollView]; 
} 

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate scrollViewWillEndDragging:scrollView withVelocity:velocity targetContentOffset:targetContentOffset]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate scrollViewWillEndDragging:scrollView withVelocity:velocity targetContentOffset:targetContentOffset]; 
} 

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate scrollViewDidEndDragging:scrollView willDecelerate:decelerate]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate scrollViewDidEndDragging:scrollView willDecelerate:decelerate]; 
} 

- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate performSelector:_cmd withObject:scrollView]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate performSelector:_cmd withObject:scrollView]; 
} 

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate performSelector:_cmd withObject:scrollView]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate performSelector:_cmd withObject:scrollView]; 
} 

- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate performSelector:_cmd withObject:scrollView]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate performSelector:_cmd withObject:scrollView]; 
} 

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView 
{ 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate performSelector:_cmd withObject:scrollView]; 
    if([origDelegate respondsToSelector:_cmd]) 
     return [origDelegate performSelector:_cmd withObject:scrollView]; 

    return nil; 
} 

- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_3_2) 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate performSelector:_cmd withObject:scrollView withObject:view]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate performSelector:_cmd withObject:scrollView withObject:view]; 
} 

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate scrollViewDidEndZooming:scrollView withView:view atScale:scale]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate scrollViewDidEndZooming:scrollView withView:view atScale:scale]; 
} 

- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView 
{ 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate scrollViewShouldScrollToTop:scrollView]; 
    if([origDelegate respondsToSelector:_cmd]) 
     return [origDelegate scrollViewShouldScrollToTop:scrollView]; 

    return false; 
} 

- (void)scrollViewDidScrollToTop:(UIScrollView *)scrollView 
{ 
    if([origDelegate respondsToSelector:_cmd]) 
     [origDelegate performSelector:_cmd withObject:scrollView]; 
    if([newDelegate respondsToSelector:_cmd]) 
     [newDelegate performSelector:_cmd withObject:scrollView]; 
} 

@end 

然後我回：

for (id subview in webView.subviews) 
    if ([[subview class] isSubclassOfClass: [UIScrollView class]]) 
    return [ProxyScrollView proxyScrollViewWithScrollView: (UIScrollView*) subview]; 

就我而言，我一直單身ProxyScrollView我的web視圖並返回。