响应UIPickerView中的touchesBegan而不是UIView

Question

我有一个UIPickerView,在不使用时会逐渐消失到20%的alpha.我希望用户能够触摸选择器并将其淡入.

如果我在主视图上放置touchesBegan方法,我可以让它工作,但这仅在用户触摸View时才有效.我尝试了UIPickerView的子类化,并在那里有一个touchesBegan,但它没有用.

我猜它与Responder链有关,但似乎无法解决.

Answer 1

一个多星期以来,我一直在寻找这个问题的解决方案.即使你的问题超过一年,我也在回答你,希望这会对别人有所帮助.

对不起,如果我的语言不是很技术,但我对Objective-C和iPhone开发很新.

子类化UIpickerView是正确的方法.但是你要覆盖这个- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event方法.无论何时触摸屏幕,都会调用此方法,并返回将对触摸作出反应的视图.换句话说,touchesBegan:withEvent:将调用其方法的视图.

UIPickerView有9个子视图!在UIPickerView类中,实现- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event将不会返回self(这意味着touchesBegan:withEvent:您在子类中的写入将不会被调用),但将返回一个子视图,完全是索引4处的视图(一个名为UIPickerTable的未记录的子类).

诀窍是使- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event方法返回self所以你必须在控制touchesBegan:withEvent:,touchesMoved:withEvent:和touchesEnded:withEvent:方法.

在这些方法中,为了保持UIPickerView的标准功能,你必须记得再次调用它们,但是在UIPickerTable子视图上.

我希望这是有道理的.我现在无法编写代码,只要我在家,我就会编辑这个答案并添加一些代码.

Answer 2

以下是一些可以满足您需求的代码:

@interface TouchDetectionView : UIPickerView {

}
- (UIView *)getNextResponderView:(NSSet *)touches withEvent:(UIEvent *)event;
@end
@implementation TouchDetectionView

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UIView * hitTestView = [self getNextResponderView:touches withEvent:event];
    [hitTestView touchesBegan:touches withEvent:event];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UIView * hitTestView = [self getNextResponderView:touches withEvent:event];
    [hitTestView touchesMoved:touches withEvent:event];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    UIView * hitTestView = [self getNextResponderView:touches withEvent:event];
    [hitTestView touchesEnded:touches withEvent:event];
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
    UIView * hitTestView = [self getNextResponderView:touches withEvent:event];
    [hitTestView touchesCancelled:touches withEvent:event];
}

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
    return self;
}

- (UIView *)getNextResponderView:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch * touch = [touches anyObject];
    CGPoint point = [touch locationInView:self];
    UIView * hitTestView = [super hitTest:point withEvent:event];

    return ( hitTestView == self ) ? nil : hitTestView;
}