How to fix strange behavior of date picker UIView when changing screen orientation in Objective-C?

问题

I have this project that requires to change the screen orientation of application once the user will pick a date using datePicker. Once the user tapped the Date button, It will show the datePicker The first image is the correct layout of the datePicker when portrait mode.

Correct Portrait Layout

When changing the screen orientation from Landscape to Portrait. It will appear the issue. Please refer to image below.

The datePicker is located below

Which is the image below should be the correct layout once turned to landscape.

When you changed the screen orientation back to portrait. The datePicker layout changed. Please refer to image below.

Incorrect Portrait Layout

Below are the codes used:

- (void)resizeView:(UIInterfaceOrientation)interfaceOrientation
{
//LOG(@"interfaceOrientation=%ld", (long)interfaceOrientation);
//LOG(@"self.frame =%@", NSStringFromCGRect(self.frame));
//LOG(@"self.bounds=%@", NSStringFromCGRect(self.bounds));

CGFloat x, y, w, h;
viewBack.frame = self.bounds;

#define _HEIGHT_LABEL   (40)
#define _HEIGHT_PICKER  (162)


#define _HEIGHT_TOOLBAR (CGRectGetHeight(toolBar.frame))//(44)
if (interfaceOrientation == UIInterfaceOrientationPortrait)
{
    LOG(@"[Portrait]");
    w = CGRectGetWidth(viewBack.frame);
    h = _HEIGHT_LABEL + _HEIGHT_PICKER*2 + _HEIGHT_TOOLBAR;
    viewPicker.frame = CGRectMake(0, 0, w, h);
    viewPicker.center = viewBack.center;

    x = 0;
    y = 0;
    w = CGRectGetWidth(viewPicker.frame);
    h = _HEIGHT_LABEL;
    lblTitle.frame = CGRectMake(x, y, w, h);

    x = 0;
    y = CGRectGetMaxY(lblTitle.frame);
    w = CGRectGetWidth(viewPicker.frame);
    h = _HEIGHT_PICKER;
    datePicker.frame = CGRectMake(x, y, w, h);

    x = 0;
    y = CGRectGetMaxY(datePicker.frame);
    w = CGRectGetWidth(viewPicker.frame);
    h = CGRectGetHeight(datePicker.frame); //datePickerと同じ
    timePicker.frame = CGRectMake(x, y, w, h);

    x = 0;
    y = CGRectGetMaxY(timePicker.frame);
    w = CGRectGetWidth(viewPicker.frame);
    h = _HEIGHT_TOOLBAR;
    toolBar.frame = CGRectMake(x, y, w, h);
    //LOG(@"tool  =%@", NSStringFromCGRect(toolBar.frame));
}
    else if (interfaceOrientation == UIInterfaceOrientationLandscapeRight)
{
    LOG(@"[Landscape]");
    w = CGRectGetWidth(viewBack.frame);
    h = _HEIGHT_LABEL + _HEIGHT_PICKER + _HEIGHT_TOOLBAR;
    viewPicker.frame = CGRectMake(0, 0, w, h);
    viewPicker.center = viewBack.center;

    x = 0;
    y = 0;
    w = CGRectGetWidth(viewPicker.frame);
    h = _HEIGHT_LABEL;
    lblTitle.frame = CGRectMake(x, y, w, h);

    w = CGRectGetWidth(viewPicker.frame) / 2; //画面幅の半分
    x = CGRectGetMidX(viewPicker.frame) - w;
    y = CGRectGetMaxY(lblTitle.frame);
    h = _HEIGHT_PICKER;
    datePicker.frame = CGRectMake(x, y, w, h);

    x = CGRectGetMidX(viewPicker.frame);
    y = CGRectGetMinY(datePicker.frame); //datePickerと同じ
    w = CGRectGetWidth(datePicker.frame); //datePickerと同じ
    h = CGRectGetHeight(datePicker.frame); //datePickerと同じ
    timePicker.frame = CGRectMake(x, y, w, h);

    x = 0;
    y = CGRectGetMaxY(datePicker.frame);
    w = CGRectGetWidth(viewPicker.frame);
    h = CGRectGetHeight(toolBar.frame);//44;
    toolBar.frame = CGRectMake(x, y, w, h);
}

 #if 0
LOG(@"back  =%@", NSStringFromCGRect(viewBack.frame));
LOG(@"base  =%@", NSStringFromCGRect(viewPicker.frame));
LOG(@"image =%@", NSStringFromCGRect(imageViewBlackGraBar.frame));
LOG(@"label =%@", NSStringFromCGRect(lblTitle.frame));
LOG(@"date  =%@", NSStringFromCGRect(datePicker.frame));
LOG(@"time  =%@", NSStringFromCGRect(timePicker.frame));
LOG(@"tool  =%@", NSStringFromCGRect(toolBar.frame));
LOG(@"");
 #endif
}

This is additional information I gathered during my investigation. Below is the .xib for portrait and landscape.

回答1:

Try calling [[self view] layoutIfNeeded]; in resizeView

or [[self view] setNeedsLayout]; when orientation occurs.

use setNeedsLayout if you are okay with the system to update it in the next upcoming update cycle use layoutIfNeeded if you want it to be updated immediately.

回答2:

You should use UITextField instead of UILabel and just set date picker as textField's inputView.

来源：https://stackoverflow.com/questions/58966673/how-to-fix-strange-behavior-of-date-picker-uiview-when-changing-screen-orientati