使用 UIPickerView 委托方法的问题答案

【问题标题】：Problems using UIPickerView delegate methods使用 UIPickerView 委托方法的问题
【发布时间】：2011-10-25 07:39:50
【问题描述】：

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。处理它：

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

触发选择选择器项未删除时发生的事件。

点击选定的选择器项目时如何触发事件？

【问题讨论】：

标签： iphone objective-c cocoa-touch uipickerview

【解决方案1】：

您必须继承 UIPickerView 并手动检测那里的触摸。是的，它看起来很乱。但这似乎是唯一的方法。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：Responding to touchesBegan in UIPickerView instead of UIView

【讨论】：