iphone - UIScrollview subview 超出剪切范围未接收触摸

Question

我有一个 UIScrollView，我将其设置为一次滑动一列(每页两列) - 通过将框架设置为 View 实际宽度的一半，将 ClipToBounds 设置为 NO 并使用 hitTest 声明外部区域框架属于 UIScrollView(请参见下面的示例)。

这很好用，但我现在的问题是 UIScrollView 的 subview 没有得到任何触摸事件 - 只有主 UIScrollView 得到。

在下面的示例中，如果包含 hitTest 代码，则 ScrollView 会正确滚动，一次分页一列，并且可以看到其所有内容 - 但内部 ScrollView 不会接收触摸事件。

如果我删除 hitTest 代码，则只有第一个子 ScrollView 接收触摸，并且可以看到其所有内容 - 但主 ScrollView 不会在非剪辑区域中获得触摸。

我该如何解决这个问题？

示例:

//=========================================
// UIScrollViewEx
// Just in order to log touches...
//=========================================

@interface UIScrollViewEx : UIScrollView {} 
@end

@implementation UIScrollViewEx
- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    NSLog(@"Touches Began (0x%08X)", (unsigned int)self);
}
@end

//=========================================
// UIViewEx
// Dummy class - sets subview as hit target
// just to demonstrate usage of non-clipped 
// content
//=========================================

@interface UIViewEx : UIView {} 
@end

@implementation UIViewEx
- (UIView *) hitTest:(CGPoint) point withEvent:(UIEvent *)event {
    if ([self pointInside:point withEvent:event]) {
        return [self.subviews objectAtIndex:0];
    }
    return nil;
}
@end

//=========================================
// MainClass
// Any UIViewEx based class which returns
// the UIScrollView child on hittest
//=========================================

@implementation MyClass

- (UIColor*) randomColor
{
    int r = arc4random() % 100;
    int g = arc4random() % 100;
    int b = arc4random() % 100;
    return [UIColor colorWithRed:(0.01 * r) green:(0.01 * g) blue:(0.01 * b) alpha:1.0];
}

- (void) loadScrollviews
{
    // Set frame to half of actual width so that paging will swipe half a page only
    CGRect frame = CGRectMake(0, 0, self.bounds.size.width / 2, 400);

    // Main scrollview
    UIScrollView *scrollview = [[UIScrollView alloc] initWithFrame:frame];
    [scrollview setBackgroundColor:[UIColor greenColor]];
    [scrollview setPagingEnabled:YES];
    [scrollview setClipsToBounds:NO];

    // Create smaller scrollviews inside it - each one half a screen wide
    const int numItems = 5;
    for(int i = 0; i < numItems; ++i) {
        frame.origin.x = frame.size.width * i;
        UIScrollView *innerScrollview = [[UIScrollViewEx alloc] initWithFrame:frame];
        [innerScrollview setContentSize:CGSizeMake(frame.size.width, 1000)];
        [innerScrollview setBackgroundColor:[self randomColor]];
        [scrollview addSubview:innerScrollview];
        [innerScrollview release];
    }

    [scrollview setContentSize:CGSizeMake(numItems * frame.size.width, frame.size.height)];

    [self addSubview:scrollview];
}

@end

更新
我通过执行以下操作将触摸转发到内部 View ，但肯定有更好的方法吗？

- (UIView *) hitTest: (CGPoint) pt withEvent: (UIEvent *) event 
{    
    if(CGRectContainsPoint(self.bounds, pt)) 
    {
        UIScrollView *scrollview = [self.subviews objectAtIndex:0];
        CGPoint scrollViewpoint = [scrollview convertPoint:pt fromView:self];

        for(UIView *view in scrollview.subviews) {
            if(CGRectContainsPoint(view.frame, scrollViewpoint)) {
                return view;
            }
        }
        return scrollview;
    } 
    else {
        return [super hitTest:pt withEvent:event];
    }
}

Answer 1

这可能有效:

- (UIView*)hitTest:(CGPoint)point withEvent:(UIEvent*)event {
    UIView* child = nil;
    if ((child = [super hitTest:point withEvent:event]) == self)
        return self.scrollView;         
    return child;
}

但是，如果 subview 超出 ScrollView 范围，则不会触发事件，并且此函数返回 self.scrollView。