Pause-code-Ausführung bis uialertview-Objekt-button gedrückt wird?

Nicht nur uialertview-Objekt zeigen nicht warten, bis der Benutzer eine Taste Antippen, es muss nicht einmal warten, bis die Alarm-Ansicht eingeblendet. Es gibt sofort.

Hinzufügen einer Kennzeichnung zu Ihrer Klasse. Wenn es NEIN, zurück NICHT aus readyToNavigateAwayFromTab und zeigen Sie Ihre Warnung. In clickedButtonAtIndex, setzen Sie das Kennzeichen, so dass readyToNavigateAwayFromTab weiß, zurückzukehren, JA. Noch in clickedButtonAtIndex, wiederholen Sie die tab-navigation von code.

Beste Lösung, die ich habe finden, ist von Sasmito Adibowo in seinem blog-post Schmerzlos Uialertview-Objekt. Er erstellt BSAlertViewDelegateBlock, eine generische UIAlertViewDelegate-Implementierung, ermöglicht die Verwendung von closures als delegate handler.

Hier ist, wie Sie es verwenden:

UIAlertView* alert = ...;
BSAlertViewDelegateBlock* alertDelegate = [[BSAlertViewDelegateBlock alloc] initWithAlertView:alert];
alertDelegate.didDismissWithButtonIndexBlock = ^(UIAlertView* alertView, NSInteger buttonIndex)
{
    switch (buttonIndex)
    {
        ...
    }
};
[alert show];

Die Umsetzung der BSAlertViewDelegateBlock.h und BSAlertViewDelegateBlock.m sind verfügbar auf GitHub, aber ich habe umgebucht, den code hier:

BSAlertViewDelegateBlock.h

#import <UIKit/UIKit.h>

/**
Adapts UIAlertViewDelegate protocol into a block-friendly interface.
*/
@interface BSAlertViewDelegateBlock : NSObject<UIAlertViewDelegate>

/**
Designated initializer.
*/
-(id) initWithAlertView:(UIAlertView*) alertView;

@property (nonatomic,strong) void(^clickedButtonAtIndexBlock)(UIAlertView* alertView,NSInteger buttonIndex);
@property (nonatomic,strong) void(^alertViewCancelBlock)(UIAlertView* alertView);
@property (nonatomic,strong) void(^willPresentAlertViewBlock)(UIAlertView* alertView);
@property (nonatomic,strong) void(^didPresentAlertViewBlock)(UIAlertView* alertView);

@property (nonatomic,strong) void(^willDismissWithButtonIndexBlock)(UIAlertView* alertView,NSInteger buttonIndex);
@property (nonatomic,strong) void(^didDismissWithButtonIndexBlock)(UIAlertView* alertView,NSInteger buttonIndex);

@property (nonatomic,strong) BOOL(^alertViewShouldEnableFirstOtherButtonBlock)(UIAlertView* alertView);

@end

BSAlertViewDelegateBlock.m

#import <objc/runtime.h>

#import "BSAlertViewDelegateBlock.h"

const char* const BSAlertViewDelegateBlockKey = "BSAlertViewDelegateBlockKey";

@interface BSAlertViewDelegateBlock ()

@property (nonatomic,weak) UIAlertView* alertView;

@end

@implementation BSAlertViewDelegateBlock

-(void) alertViewDelegateBlock_cleanup
{
UIAlertView* alertView = self.alertView;
//remove all handler blocks in case one of these blocks inadvertendly caused a circular reference to this delegate object.
self.clickedButtonAtIndexBlock = nil;
self.alertViewCancelBlock = nil;
self.willPresentAlertViewBlock = nil;
self.didPresentAlertViewBlock = nil;
self.willDismissWithButtonIndexBlock = nil;
self.didDismissWithButtonIndexBlock = nil;
self.alertViewShouldEnableFirstOtherButtonBlock = nil;
//finally remove this delegate from the alert view
if (alertView.delegate == self) {
alertView.delegate = nil;
objc_setAssociatedObject(alertView, BSAlertViewDelegateBlockKey, nil, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
}

-(id) initWithAlertView:(UIAlertView *)alertView
{
if (self = [super init]) {
self.alertView = alertView;
objc_setAssociatedObject(alertView, BSAlertViewDelegateBlockKey, self, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
alertView.delegate = self;
}
return self;
}


#pragma mark UIAlertViewDelegate

//Called when a button is clicked. The view will be automatically dismissed after this call returns
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
void(^clickedButtonAtIndexBlock)(UIAlertView* alertView,NSInteger buttonIndex) = self.clickedButtonAtIndexBlock;
if (clickedButtonAtIndexBlock) {
clickedButtonAtIndexBlock(alertView,buttonIndex);
}
}

//Called when we cancel a view (eg. the user clicks the Home button). This is not called when the user clicks the cancel button.
//If not defined in the delegate, we simulate a click in the cancel button
- (void)alertViewCancel:(UIAlertView *)alertView
{
void(^alertViewCancelBlock)(UIAlertView* alertView) = self.alertViewCancelBlock;
if (alertViewCancelBlock) {
alertViewCancelBlock(alertView);
}
[self alertViewDelegateBlock_cleanup];
}

- (void)willPresentAlertView:(UIAlertView *)alertView
{
void(^willPresentAlertViewBlock)(UIAlertView* alertView) = self.willPresentAlertViewBlock;
if (willPresentAlertViewBlock) {
willPresentAlertViewBlock(alertView);
}
}


- (void)didPresentAlertView:(UIAlertView *)alertView
{
void(^didPresentAlertViewBlock)(UIAlertView* alertView) = self.didPresentAlertViewBlock;
if (didPresentAlertViewBlock) {
didPresentAlertViewBlock(alertView);
}
}


- (void)alertView:(UIAlertView *)alertView willDismissWithButtonIndex:(NSInteger)buttonIndex
{
void(^willDismissWithButtonIndexBlock)(UIAlertView* alertView,NSInteger buttonIndex) = self.willDismissWithButtonIndexBlock;
if (willDismissWithButtonIndexBlock) {
willDismissWithButtonIndexBlock(alertView,buttonIndex);
}
}


- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
void(^didDismissWithButtonIndexBlock)(UIAlertView* alertView,NSInteger buttonIndex) = self.didDismissWithButtonIndexBlock;
if (didDismissWithButtonIndexBlock) {
didDismissWithButtonIndexBlock(alertView,buttonIndex);
}
[self alertViewDelegateBlock_cleanup];
}


- (BOOL)alertViewShouldEnableFirstOtherButton:(UIAlertView *)alertView
{
BOOL(^alertViewShouldEnableFirstOtherButtonBlock)(UIAlertView* alertView) = self.alertViewShouldEnableFirstOtherButtonBlock;
if (alertViewShouldEnableFirstOtherButtonBlock) {
return alertViewShouldEnableFirstOtherButtonBlock(alertView);
}

//default to enable.
return YES;
}


@end