Mi è piaciuto l'approccio adottato da Wayfarer e flexaddicted, ma ho scoperto (come aZtral) che non funzionava poiché backgroundTapButton era l'unico elemento che rispondeva all'interazione dell'utente. Questo mi ha portato a mettere tutte e tre le sue sottoview: _picker, _pickerToolbar e backgroundTapButton all'interno di una vista contenitore (popup) che è stata quindi animata dentro e fuori dallo schermo. Avevo anche bisogno di un pulsante Annulla sulla _pickerToolbar. Di seguito sono riportati gli elementi di codice rilevanti per la visualizzazione popup (è necessario fornire la propria origine dati di selezione e metodi delegati).
#define DURATION 0.4
#define PICKERHEIGHT 162.0
#define TOOLBARHEIGHT 44.0
@interface ViewController ()
@property (nonatomic, strong) UIView *popup;
@property (nonatomic, strong) UIPickerView *picker;
@property (nonatomic, strong) UIToolbar *pickerToolbar;
@property (nonatomic, strong) UIButton *backgroundTapButton;
@end
-(void)viewDidLoad {
// These are ivars for convenience
rect = self.view.bounds;
topNavHeight = self.navigationController.navigationBar.frame.size.height;
bottomNavHeight = self.navigationController.toolbar.frame.size.height;
navHeights = topNavHeight + bottomNavHeight;
}
-(void)showPickerView:(id)sender {
[self createPicker];
[self createToolbar];
// create view container
_popup = [[UIView alloc] initWithFrame:CGRectMake(0.0, topNavHeight, rect.size.width, rect.size.height - navHeights)];
// Initially put the centre off the bottom of the screen
_popup.center = CGPointMake(rect.size.width / 2.0, rect.size.height + _popup.frame.size.height / 2.0);
[_popup addSubview:_picker];
[_popup insertSubview:_pickerToolbar aboveSubview:_picker];
// Animate it moving up
// This seems to work though I am not sure why I need to take off the topNavHeight
CGFloat vertCentre = (_popup.frame.size.height - topNavHeight) / 2.0;
[UIView animateWithDuration:DURATION animations:^{
// move it to a new point in the middle of the screen
[_popup setCenter:CGPointMake(rect.size.width / 2.0, vertCentre)];
} completion:^(BOOL finished) {
// When done, place an invisible 'button' on the view behind the picker,
// so if the user "taps to dismiss" the picker, it will go away
self.backgroundTapButton = [UIButton buttonWithType:UIButtonTypeCustom];
_backgroundTapButton.frame = CGRectMake(0, 0, _popup.frame.size.width, _popup.frame.size.height);
[_backgroundTapButton addTarget:self action:@selector(doneAction:) forControlEvents:UIControlEventTouchUpInside];
[_popup insertSubview:_backgroundTapButton belowSubview:_picker];
[self.view addSubview:_popup];
}];
}
-(void)createPicker {
// To use the default UIPickerView frame of 216px set frame to CGRectZero, but we want the 162px height one
CGFloat pickerStartY = rect.size.height - navHeights - PICKERHEIGHT;
self.picker = [[UIPickerView alloc] initWithFrame:CGRectMake(0.0, pickerStartY, rect.size.width, PICKERHEIGHT)];
_picker.dataSource = self;
_picker.delegate = self;
_picker.showsSelectionIndicator = YES;
// Otherwise you can see the view underneath the picker
_picker.backgroundColor = [UIColor whiteColor];
_picker.alpha = 1.0f;
}
-(void)createToolbar {
CGFloat toolbarStartY = rect.size.height - navHeights - PICKERHEIGHT - TOOLBARHEIGHT;
_pickerToolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, toolbarStartY, rect.size.width, TOOLBARHEIGHT)];
[_pickerToolbar sizeToFit];
NSMutableArray *barItems = [[NSMutableArray alloc] init];
UIBarButtonItem *cancelButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCancel target:self action:@selector(cancelAction:)];
[barItems addObject:cancelButton];
// Flexible space to make the done button go on the right
UIBarButtonItem *flexSpace = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:self action:nil];
[barItems addObject:flexSpace];
// The done button
UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(doneAction:)];
[barItems addObject:doneButton];
[_pickerToolbar setItems:barItems animated:YES];
}
// The method to process the picker, if we have hit done button
- (void)doneAction:(id)sender {
[UIView animateWithDuration:DURATION animations:^{
_popup.center = CGPointMake(rect.size.width / 2.0, rect.size.height + _popup.frame.size.height / 2.0);
} completion:^(BOOL finished) { [self destroyPopup]; }];
// Do something to process the returned value from your picker
}
// The method to process the picker, if we have hit cancel button
- (void)cancelAction:(id)sender {
[UIView animateWithDuration:DURATION animations:^{
_popup.center = CGPointMake(rect.size.width / 2.0, rect.size.height + _popup.frame.size.height / 2.0);
} completion:^(BOOL finished) { [self destroyPopup]; }];
}
-(void)destroyPopup {
[_picker removeFromSuperview];
self.picker = nil;
[_pickerToolbar removeFromSuperview];
self.pickerToolbar = nil;
[self.backgroundTapButton removeFromSuperview];
self.backgroundTapButton = nil;
[_popup removeFromSuperview];
self.popup = nil;
}
