Set UIAlertView delegate - ios

Question

I try to have the delegate method called but it isn't. What should I change in my code? Thank you.
I tried to add in Class1.m:
+(void)popupAlert:(NSString*)msg tag:(NSInteger)tag{
Class1 *c= [[Class1 alloc]init];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#""
message:msg
delegate:c (I also tried c.self)
cancelButtonTitle:...
otherButtonTitles:...,nil];
alert.tag=tag;
[alert show];
}
I try to set alertview delegate to make this delegate method called.
-(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
Here is what I'm doing:
Class1.h:
+(void)popupAlert:(NSString*)msg tag:(NSInteger)tag;
Class1.m:
+(void)popupAlert:(NSString*)msg tag:(NSInteger)tag{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#""
message:msg
delegate:self
cancelButtonTitle:...
otherButtonTitles:...,nil];
alert.tag=tag;
[alert show];
}
-(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex{
//some coding
}
Class2.m:
-(void)func1{
[Class1 popupAlert:#"blah blah" tag:0];
}

Answer 1

It seems c gets dealloced right after [alert show]; because there are no strong reference pointing to this object afterwards and the delegate becomes nil;
In other example you should turn instance method
-(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
to class method:
+(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex

Answer 2

Rethink your architecture.
You are creating the alert in a class method. (That is indicated by the leading + instead of -). Within that self is a reference to the class, not the object.
alertView:didDismissWithButtonIndex: is an instance method. I am not even sure that you could apply a delegate protocol to the class instead of the instances. But if you can, then your delegate method would have to be a class method too.
+(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
Well, I am just thinking of that and DO NOT PROMISE that it works that way.
If I were you I'd go for a singleton pattern and use instance methods to throw the alert and to respond to the delegate protocol.
Anyway, I am wondering which warning xcode displays on delegate:self and why you are not telling us about the warning. Warnings are there for a reason.

Answer 3

Alertview delegate property is week reference.
So once you finished the +(void)popupAlert:(NSString*)msg tag:(NSInteger)tag method then all local variables on Stack will removed from memory.
means destroyed. So even you set the delegate there it wont work.
#property(nonatomic,assign) id /*<UIAlertViewDelegate>*/ delegate;
So you should do like this
-(void)func1{
Class1 *class1 = [[Class1 alloc] init];
[Class1 popupAlert:#"blah blah" tag:0 withDelegate:class1];
}
+(void)popupAlert:(NSString*)msg tag:(NSInteger)tag withDelegate:(id)delegateOfAlert]{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#""
message:msg
delegate:delegateOfAlert
cancelButtonTitle:...
otherButtonTitles:...,nil];
alert.tag=tag;
[alert show];
}