iOS development-auto-disappearing pop-up box

-(void) Timerfiremethod: (nstimer*) thetimer//popup box {    Uialertview *promptalert = (uialertview*) [Thetimer userInfo];    [Promptalert dismisswithclickedbuttonindex:0 Animated:no];    Promptalert =null;} -(void) Showalert: (NSString *) _message{//time    Uialertview *promptalert = [[Uialertview alloc] initwithtitle:@ "prompt:" Message:_message Delegate:nil Cancelbuttontitle:nil Otherbuttontitles:nil];       [Nstimer scheduledtimerwithtimeinterval:1.5f                                     target:self                                   selector: @selector (timerfiremethod:)                                   Userinfo:promptalert                                    Repeats:yes];    [Promptalert show];}

Call the [self showalert:@ "test] in place where you need to display the popup box;

Principle: When the pop-up, set a timer.  After 1.5 seconds, the current pop-up box is set empty. (Promptalert =null;)