Я добавил несколько комментариев для ясности, поправьте меня, если я ошибаюсь (я недавно начал разрабатывать для iOS). Спасибо Матиасу Бауху! Ваш пример кода уже очень помог мне и дал много понимания. Я надеюсь, что эти комментарии сделают то же самое для других.
/*
* Is called when the date is changed by the user.
*/
- (void)changeDate:(UIDatePicker *)sender {
NSLog(@"New Date: %@", sender.date);
}
/*
* Releases the background, datepicker and toolbar.
*/
- (void)removeViews:(id)object {
/*
* Releases the background view.
*/
[[self.view viewWithTag:9] removeFromSuperview];
/*
* Releases the datepicker.
*/
[[self.view viewWithTag:10] removeFromSuperview];
/*
* Releases the toolbar.
*/
[[self.view viewWithTag:11] removeFromSuperview];
}
/*
* Hides the datapicker.
*/
- (void)dismissDatePicker:(id)sender {
/*
* Create a variable with the target position and size for hiding the toolbar.
*/
CGRect toolbarTargetFrame = CGRectMake(0, self.view.bounds.size.height, 320, 44);
/*
* Create a variable with the target position and size for hiding the datepicker.
*/
CGRect datePickerTargetFrame = CGRectMake(0, self.view.bounds.size.height + 44, 320, 216);
/*
* Send start animation message to UIView.
*/
[UIView beginAnimations:@"MoveOut" context:nil];
/*
* Set the transparency for hiding the background view.
*/
[self.view viewWithTag:9].alpha = 0;
/*
* Set the target position for hiding the datepicker.
*/
[self.view viewWithTag:10].frame = datePickerTargetFrame;
/*
* Set the target position for hiding the toolbar.
*/
[self.view viewWithTag:11].frame = toolbarTargetFrame;
/*
* The method setAnimationDelegate enables knowledge on start and end of the animation.
*/
[UIView setAnimationDelegate:self];
/*
* Calls the removeViews method at the end of the animation.
*/
[UIView setAnimationDidStopSelector:@selector(removeViews:)];
/*
* Commits the animation thread for execution.
*/
[UIView commitAnimations];
}
/*
* Sets up and shows the datepicker.
*/
- (IBAction)callDP:(id)sender {
/*
* If view with tag exists ignore the rest of the code and exit.
*/
if([self.view viewWithTag:9]) {
return;
}
/*
* Create a variable with the target position and size for showing the toolbar.
*/
CGRect toolbarTargetFrame = CGRectMake(0, self.view.bounds.size.height - 216 - 44, 320, 44);
/*
* Create a variable with the target position and size for showing the datepicker.
*/
CGRect datePickerTargetFrame = CGRectMake(0, self.view.bounds.size.height - 216, 320, 216);
/*
* Instantiate a UIView with the frame size of the existing view.
*/
UIView *darkView = [[UIView alloc] initWithFrame:self.view.bounds];
/*
* Set the transparency.
*/
darkView.alpha = 0;
/*
* Set the background color.
*/
darkView.backgroundColor = [UIColor blackColor];
/*
* Set a tag for the UIView instance to reference it by tag.
*/
darkView.tag = 9;
/*
* Setup a tap gesture listener that calls the dismissDatePicker method on tap.
*/
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dismissDatePicker:)];
/*
* Add the tap gesture listener to the UIView.
*/
[darkView addGestureRecognizer:tapGesture];
/*
* Adds the subview on top of all the other subviews.
*/
[self.view addSubview:darkView];
/*
* Instantiate a UIDatePicker and set the initial frame with the datepicker outside of the view.
*/
UIDatePicker *datePicker = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, self.view.bounds.size.height+44, 320, 216)];
/*
* Set a tag for the UIDatePicker instance to reference it by tag.
*/
datePicker.tag = 10;
/*
* Add a listener that listens for changing values in the datepicker which then calls the change date method.
*/
[datePicker addTarget:self action:@selector(changeDate:) forControlEvents:UIControlEventValueChanged];
/*
* Adds the subview on top of all the other subviews.
*/
[self.view addSubview:datePicker];
/*
* Instantiate a UIToolbar and set the initial frame with the toolbar outside of the view.
*/
UIToolbar *toolBar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, self.view.bounds.size.height, 320, 44)];
/*
* Set a tag for the UIToolbar instance to reference it by tag.
*/
toolBar.tag = 11;
/*
* Set a style for the UIToolbar.
*/
toolBar.barStyle = UIBarStyleBlackTranslucent;
/*
* Instantiate a spacer UIBarButtonItem.
*/
UIBarButtonItem *spacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
/*
* Instantiate a done UIBarButtonItem on click this will call the dismissDatePicker method.
*/
UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(dismissDatePicker:)];
/*
* Set the created UIBarButtonItems to the toolbar.
*/
[toolBar setItems:[NSArray arrayWithObjects:spacer, doneButton, nil]];
/*
* Adds the subview on top of all the other subviews.
*/
[self.view addSubview:toolBar];
/*
* Start animation.
*/
[UIView beginAnimations:@"MoveIn" context:nil];
/*
* Set the target position for showing the toolbar.
*/
toolBar.frame = toolbarTargetFrame;
/*
* Set the target position for showing the datepicker.
*/
datePicker.frame = datePickerTargetFrame;
/*
* Set the transparency for showing background view.
*/
darkView.alpha = 0.5;
/*
* Commits the animation thread for execution.
*/
[UIView commitAnimations];
}