ios - alertViewShouldEnableFirstOtherButton not called -

i want show uialertview textfield. , if user has not entered valid emai id ok button of uialertview disable.

i know how show uialertview , disable uialertview ok button ..

my problem -(bool)alertviewshouldenablefirstotherbutton:(uialertview *)alertview not called thats why button enabled.

but when user press ok button

- (void)alertview:(uialertview *)alertview clickedbuttonatindex:(nsinteger)buttonindex 

is called.

here code ,

-(ibaction)forgotpassbtnclicked:(id)sender { uialertview *alertview=[[uialertview alloc]initwithtitle:@"" message:@"" delegate:self cancelbuttontitle:@"ok" otherbuttontitles:nil, nil]; [alertview setalertviewstyle:uialertviewstyleplaintextinput]; uitextfield *textfield=[alertview textfieldatindex:0]; textfield.placeholder=@"enter email id"; [alertview show]; }    #pragma  mark alertview delgate - (bool)alertviewshouldenablefirstotherbutton:(uialertview *)alertview {  uitextfield *text1=[alertview textfieldatindex:0]; bool flag=[self validateemail:text1.text]; return flag;  } - (void)alertview:(uialertview *)alertview clickedbuttonatindex:(nsinteger)buttonindex {  }  #pragma mark email validation - (bool) validateemail: (nsstring *) email  { nsstring *emailregex = @"[a-z0-9a-z._%+-]+@[a-za-z0-9.-]+\\.[a-za-z]{2,4}"; nspredicate *emailtest = [nspredicate predicatewithformat:@"self matches %@", emailregex]; //  return 0; return [emailtest evaluatewithobject:email]; } 

i don't understand doing wrong?..

thanks in advance...

uialertviewdelegate documentation says alertviewshouldenablefirstotherbutton: method,

sent delegate determine whether first non-cancel button ion alert should enabled.

you creating alert cancel button @"ok", since non-cancel buttons nil method not getting called. instead try following,

uialertview *alertview=[[uialertview alloc]initwithtitle:@"" message:@"" delegate:self cancelbuttontitle:@"cancel" otherbuttontitles:@"ok", nil]; 

also, user should have option cancel alert without having enter text. user experience have cancel button.