Cannot show UIAlertView with a text field - iphone

Question

This piece of code which is supposed to show an alert window with a text input:
self.alert = [[UIAlertView alloc] initWithTitle:#"Hello" message:#"How are you?" delegate:self cancelButtonTitle:#"Cancel" otherButtonTitles:#"OK", nil];
self.alert.alertViewStyle = UIAlertViewStylePlainTextInput;
[self.alert show];
Causes this error:
Thread 7: Program received signal: "EXC_BAD_ACCESS"
This is how self.alert is defined:
#interface MyClass : NSObject
{
UIAlertView *alert;
id <MyClassDelegate> __unsafe_unretained delegate;
}
#property (nonatomic, retain) UIAlertView *alert;
#property (unsafe_unretained) id <MyClassDelegate> delegate;

Answer 1

The problem is maybe because of the customize.
I do not know why, but appear to me that the problem is because of the use of threads + customize of your alert.
Can you try to show this alert on the main thread? What happen?
You probably get an error in this line:
self.alert.alertViewStyle = UIAlertViewStylePlainTextInput;
What you need to do if yes, is perform this in the main thread.
- (void) yourMethod{
[self performSelectorOnMainThread:#selector(yourMethod2) withObject:nil waitUntilDone:NO];
}
- (void) yourMethod2{
self.alert = [[UIAlertView alloc] initWithTitle:#"Hello" message:#"How are you?" delegate:self cancelButtonTitle:#"Cancel" otherButtonTitles:#"OK", nil];
self.alert.alertViewStyle = UIAlertViewStylePlainTextInput;
[self.alert show];
}
Sorry to can't help you more than that, but I do not know exactly what happen, but I already read about issues when editing things to show, in other threads.
Hope it help you!

Answer 2

The EXC_BAD_ACCESS is caused by accessing a released object. To avoid this make your call to UIAlertView kind of modal:
Function body:
-(void)checkSaving
{
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:#"Do you want to add these results to your database?"
message:#"\n\n"
delegate:self
cancelButtonTitle:#"No"
otherButtonTitles:#"Save", nil];
alert.alertViewStyle = UIAlertViewStyleDefault;
[alert show];
//this prevent the ARC to clean up :
NSRunLoop *rl = [NSRunLoop currentRunLoop];
NSDate *d;
d= (NSDate*)[d init];
while ([alert isVisible])
{
[rl runUntilDate:d];
}
}
Your choice result:
- (void)alertView:(UIAlertView *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
// the user clicked one of the OK/Cancel buttons
if (buttonIndex == 1)//Save
{
//do something
}
if (buttonIndex == 0)//NO
{
//do something
}
}
Register the functions in the interface declaration:
#interface yourViewController ()
-(void)checkSaving
- (void)alertView:(UIAlertView *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
//...
#end
To call:
[self checkSaving];
I wish this will help you.