检查 UIPickerView 是显示还是隐藏？ *if* 条件？

Question

我的 UIPickerView 动画有一点问题。 我确实设置了动画，因此当我单击按钮时 UIPickerView 将向上滑动，再次单击后它将向下滑动。但我在 if 上遇到了问题。我尝试设置一个新的设置布尔值，并在每个动画之后设置它的值，因此 if 只是检查布尔值。我不确定我是否解释得很好，但也许您从代码中得到了这个想法。 但不幸的是它不起作用......有什么想法吗？

- (void)viewDidLoad
{
    [super viewDidLoad];

    settings = [NSUserDefaults standardUserDefaults];
    [settings setBool:NO forKey:@"pickerShown"];
    [settings synchronize];
}


- (IBAction)showPicker:(id)sender {

    CGRect rect = countryPicker.frame;
    CGPoint origin = CGPointMake(0, 510); // Some off-screen y-offset here.

    rect.origin = origin;
    countryPicker.frame = rect;


    if ([settings boolForKey:@"pickerShown"] == YES) {


        // Perform transform to slide it off the screen.
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:0.5];
        countryPicker.transform = CGAffineTransformMakeTranslation(0, -0); // Offset.
        [UIView commitAnimations];
        [settings setBool:NO forKey:@"pickerShown"];
        [settings synchronize];

    } else if ([settings boolForKey:@"pickerShown"] == NO) {


        // Perform transform to slide it onto the screen.
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:0.5];
        countryPicker.transform = CGAffineTransformMakeTranslation(0, -266); // Offset.
        [UIView commitAnimations];
        [settings setBool:YES forKey:@"pickerShown"];
        [settings synchronize];

    }
}

编辑：

刚刚找到解决方案... 如果有人感兴趣 - 这是：

h。文件：

.
.
.
{
BOOL pickerShown;
}
.
.
.

.m 文件：

- (void)viewDidLoad
{
    [super viewDidLoad];

    CGRect rect = countryPicker.frame;
    CGPoint origin = CGPointMake(0, 510); // Some off-screen y-offset here.

    rect.origin = origin;
    countryPicker.frame = rect;
pickerShown = NO;


}


- (IBAction)showPicker:(id)sender {


    if (pickerShown == NO) {


        // Perform transform to slide it onto the screen.
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:1];
        //[UIView setAnimationDidStopSelector:@selector(hidePicker)];
        countryPicker.transform = CGAffineTransformMakeTranslation(0, 0); // Offset.
        [UIView commitAnimations];
        [self performSelector:@selector(hidePicker) withObject:nil afterDelay:1];

    } else if (pickerShown == YES) {

        //countryPicker.hidden = NO;
        // Perform transform to slide it onto the screen.
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:1];
        countryPicker.transform = CGAffineTransformMakeTranslation(0, -266); // Offset.
        [UIView commitAnimations];
        countryPicker.hidden = NO;

    }
}

Answer 1

如果视图在屏幕上可见，则其 window 属性将为非零。

Answer 2

您可以通过以下方式检查：

self.countryPicker.superview

如果选择器隐藏，则超级视图将为nil。否则它将包含视图。

Answer 3

刚刚找到了解决方案...如果有人感兴趣 - 这里是：

h。文件：

.
.
.
{
BOOL pickerShown;
}
.
.
.

.m 文件：

- (void)viewDidLoad
{
    [super viewDidLoad];

    CGRect rect = countryPicker.frame;
    CGPoint origin = CGPointMake(0, 510); // Some off-screen y-offset here.

    rect.origin = origin;
    countryPicker.frame = rect;
pickerShown = NO;


}


- (IBAction)showPicker:(id)sender {


    if (pickerShown == NO) {


        // Perform transform to slide it onto the screen.
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:1];
        //[UIView setAnimationDidStopSelector:@selector(hidePicker)];
        countryPicker.transform = CGAffineTransformMakeTranslation(0, 0); // Offset.
        [UIView commitAnimations];
        [self performSelector:@selector(hidePicker) withObject:nil afterDelay:1];

    } else if (pickerShown == YES) {

        //countryPicker.hidden = NO;
        // Perform transform to slide it onto the screen.
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:1];
        countryPicker.transform = CGAffineTransformMakeTranslation(0, -266); // Offset.
        [UIView commitAnimations];
        countryPicker.hidden = NO;

    }
}

Answer 4

如果您想要的只是显示选取器视图的基本效果，那么再次删除它有一种更简单的方法。

伪代码：

//do any picker initialization here

if(!pickerIsShowing)
[self.view addSubview:yourPickerView];
else
 [self.yourPickerView removeFromSuperView];