Question

Hi I was wondering how can I call a method just for one time in application life … My application should download some files from server and I need do it just for one time; I mean mean just one time per installation

here is my method

//Download some images from server and save it into directory 

- (void) downloadCovers {

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    [self saveFile:@"mag1" ofType:@"png" fromURL:@"http://myweb.com/mag1.png" inDirectory:documentsDirectory];

}

and this method set images as UIButton BG :

  - (void)buttonsBGImage {

       UIImage * bgMag1 = [self loadImage:@"mag1" ofType:@"png" inDirectory:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]];

        [mag1 setBackgroundImage:bgMag1 forState:UIControlStateNormal];
         NSLog(@"BG IS SET");

    }

Answer 1

Set a flag as a NSUserDefaults key and check for this NSUserDefault value in your downloadCovers method. If it is already set, do nothing, else download files and set the flag to true.

Like so:

-(void) downloadCovers {
BOOL downloaded = [[NSUserDefaults standardUserDefaults] boolForKey: @"downloaded"];
if (!downloaded) {
     //download code here
      [[NSUserDefaults standardUserDefaults] setBool:YES forKey: @"downloaded"];
    }
}

Cheers