is there easy way to handle UIAlertView result without delegation? - iphone

Question

I have a function that shows a UIAlertView with YES/NO buttons, and it is used only inside the function's scope so I dont want to implement a delegation to catch the user feedback.
Is there any way to know what button users clicked without implement UIAlertViewDelegate, something like:
[alert show];
if([alert indexOfClickedButton] == indexOfYes)
{
....
}
Or lambda expression as in Animation

Answer 1

There is no way to avoid delegation completely, but you could create a wrapper to that effect along these lines:
#interface MyAlertViewDelegate : NSObject<UIAlertViewDelegate>
typedef void (^AlertViewCompletionBlock)(NSInteger buttonIndex);
#property (strong,nonatomic) AlertViewCompletionBlock callback;
+ (void)showAlertView:(UIAlertView *)alertView withCallback:(AlertViewCompletionBlock)callback;
#end
#implementation MyAlertViewDelegate
#synthesize callback;
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
callback(buttonIndex);
}
+ (void)showAlertView:(UIAlertView *)alertView
withCallback:(AlertViewCompletionBlock)callback {
__block MyAlertViewDelegate *delegate = [[MyAlertViewDelegate alloc] init];
alertView.delegate = delegate;
delegate.callback = ^(NSInteger buttonIndex) {
callback(buttonIndex);
alertView.delegate = nil;
delegate = nil;
};
[alertView show];
}
#end
(ARC is assumed, if you are not using it change delegate = nil to [delegate release].)
Usage would be something like:
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Confirm" message:#"Yes or No?" delegate:nil cancelButtonTitle:#"Cancel" otherButtonTitles:#"Yes",#"No", nil];
[MyAlertViewDelegate showAlertView:alert withCallback:^(NSInteger buttonIndex) {
// code to take action depending on the value of buttonIndex
}];

Answer 2

I have written a blog post about how to (and why) add block callbacks to alert views, action sheets and animations:
http://blog.innovattic.com/uikitblocks/
If you just want a working implementation of this you can download the sources files from GitHub:
https://github.com/Innovattic/UIKit-Blocks
Usage:
UIAlertView* alert = [[UIAlertView alloc] initWithTitle:#"My easy alert"
message:#"Would you like to perform some kind of action?"
cancelButtonTitle:#"No"
otherButtonTitles:#"Yes", nil];
[alert setHandler:^(UIAlertView* alert, NSInteger buttonIndex) {
NSLog(#"Perform some kind of action");
} forButtonAtIndex:[alert firstOtherButtonIndex]];
[alert show];

Answer 3

It's very easy. Say you have an alert, something like this:
//Alert
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Confirm" message:#"Yes or No?" delegate:self cancelButtonTitle:#"Cancel" otherButtonTitles:#"Yes",#"No", nil];
[alert show];
You're going to need to add this method:
- (void)alertView:(UIAlertView *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
A possible implementation of this method would look like this:
- (void)alertView:(UIAlertView *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
//Checks For Approval
if (buttonIndex == 1) {
//do something because they selected button one, yes
} else {
//do nothing because they selected no
}
}

Answer 4

You can do this using custom view which can be hidden and shown to avoid ActionSheets
UIView *AlertVw=[UIView alloc]initWithFrame:CGRect(x,y,w,h)]];
UIButton *SaveButton=[UIButton alloc]initWithFrame:CGRect(x,y,w,h)]];
[CustomButton setTitle:#"Ok" forState:UIControlStateNormal];
[SaveButton addTarget:self action:#selector(SaveClicked) forControlEvents:UIControlEventTouchUpInside];
UIButton *CancelButton=[UIButton alloc]initWithFrame:CGRect(x,y,w,h)]];
[CustomButton setTitle:#"Cancel" forState:UIControlStateNormal];
[CancelButton addTarget:self action:#selector(CancelClicked) forControlEvents:UIControlEventTouchUpInside];
[AlertVw addSubview:SaveButton];
[AlertVw addSubview:CancelButton];
[self.view addSubview:AlertVw];
-(void)SaveButton
{
//Code to apply on Save clicked
[AlertVw removeFromSuperView]; //Also you can use AlertView.hidden=YES;
}
-(void)CancelButton
{
//Code to apply on cancel clicked
[AlertVw removeFromSuperView]; //Also you can use AlertView.hidden=YES;
}

Answer 5

No need to derive the class. With Block, it is easy to get user selected button index.
typedef void(^AlertViewCallBackBlock)(NSInteger selectedIndex);
#interface ABC ()
#property (nonatomic, copy) AlertViewCallBackBlock alertViewBlock;
#end
#implementation
- (void)showAlert {
self.alertViewBlock = ^(NSInteger selectedIndex) {
if (selectedIndex == 1) {
}
};
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Confirm" message:#"Yes or No?" delegate:self cancelButtonTitle:#"Cancel" otherButtonTitles:#"Yes",#"No", nil];
[alert show];
}
- (void)alertView:(UIAlertView *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
self.alertViewBlock(buttonIndex);
}
#end

Answer 6

Thanks Arkku. Here is the Swift version.
https://github.com/exchangegroup/alert-view-with-callback-swift
let alertView = UIAlertView(...)
AlertViewWithCallback().show(alertView) { alertView, buttonIndex in
println("You closed alert by tapping button #\(buttonIndex)")
}

Answer 7

UIAlertView is deprecated from iOS 8.0, a better solution will be using UIAlertController:
let alert = UIAlertController(title: "message", message: "Title", preferredStyle: .Alert)
alert.addAction(UIAlertAction(title: "YES", style: .Default, handler: { (action) -> Void in
// Action for YES
}))
alert.addAction(UIAlertAction(title: "NO", style: .Default, handler: { (action) -> Void in
// Action for NO
}))
self.view.window!.rootViewController!.presentViewController(alert, animated: true, completion: nil)