使用 UIPickerView 委托方法的问题

Question

我有一个 UIPicker 并设置了我的委托方法。

我希望当用户点击选定的选择器项目时发生一些事情。处理方式：

- (void)pickerView:(UIPickerView *)aPickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component

当选择选择器项而不是点击时触发事件发生。

当点击选定的选择器项目时，如何触发事件？

Answer 1

您必须子类 UIPickerView 并手动检测那里的触摸。是的，看起来很乱。但这似乎是做到这一点的唯一方法。下面的代码可能会有所帮助，

@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;
}

参考：在UIPickerView而不是UIView中响应touchesBegan