Set the timer on the

I created a new project, named yiqi, the project generated a yiqiViewController.xib file through IB, I joined a label, the default text is "welcome", ID is showtxt, has passed the File's Owner point, and then I yiqiViewController.m file write the following code, the purpose is to more than 5 seconds, the welcome text into 1234


@ Implementation yiqiViewController

- (Void) applicationDidFinishLaunching: (id) unused
{

NSTimer * timer = [NSTimer scheduledTimerWithTimeInterval: 5 target: self selector: @ selector (onTimer :) userInfo: nil repeats: NO];

}

- (Void) onTimer: (NSTimer *) timer {

[Showtxt setText: @ "1234"];

}

@ End

When we encounter two problems
One: There is a yellow warning, suggesting that the warning: unused variable 'timer' (text plus red line)

Two: After five seconds later, label display, or welcome, rather than 1234

What does this code wrong place?
Reply:
You do not just create a timer variable use.
start timer is not to have a start method.

Check Apple's documentation.
Reply:
yiqiViewController.m how to call - (void) applicationDidFinishLaunching:? ? ?
You debug, the phrase is being generated timer is running?

I suggest you use - (void) viewDidLoad or - (void) viewWillAppear: and so

applicationDidFinishLaunching: should appDelegate inside.
Reply:
Yes, finally, do not forget to turn off the timer

[Timer invalidate];
timer = nil; / / Make sure you do not have a timer invalidate being used!