iphone - 隐藏/显示 UIPickerView

Question

我有一个 TouchsEnded 事件，用于检查何时按下 UITextField。我希望它做的是隐藏/显示 UIPickerView。如何做到这一点？

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
    UITouch *touch = [[event allTouches] anyObject];
    if (CGRectContainsPoint([self.textField frame], [touch locationInView:self.view]))
    {
        NSString * error = @"Touched the TextField";
        UIAlertView * errorAlert = [[UIAlertView alloc] initWithTitle:@"Selection!" message:error delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [errorAlert show];
        //Want to show or hide UIPickerView
    }
}

当触摸发生时，我已经分配了 UIPickerView

@interface ThirdViewController : UIViewController <UITextFieldDelegate,UIPickerViewDelegate> {
    IBOutlet UIPickerView *pickerView;
}

Answer 1

切换“隐藏”属性可以达到目的，但也会带来非常突然的显示。

避免这种情况的一种方法是将选择器嵌入 UIActionSheet 中，使其从屏幕底部向上滑动。

这是一个例子:

    UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:nil 
delegate:nil cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:nil];

    CGRect pickerFrame = CGRectMake(0, 0, 0, 0);
    UIPickerView *pickerView = [[UIPickerView alloc] initWithFrame:pickerFrame];
    pickerView.showsSelectionIndicator = YES;
    pickerView.dataSource = self;
    pickerView.delegate = self;
    [sheet addSubview:pickerView];
    [pickerView release];

    [sheet showInView:view];
    [sheet setBounds:CGRectMake(0, 0, 320, 415)];
    self.actionSheet = sheet; // assuming you have setup a property to hold the action sheet
    [sheet release];

使用完选择器后，将其关闭:

[self.actionSheet dismissWithClickedButtonIndex:0 animated:YES];

这种方法也可用于在选择器上方的栏中合并按钮(“完成”、“上一个”、“下一个”等) - 关于如何做到这一点有一个很好的解释 here .