arc4random - how can i make my random text generator not repeat until all texts have been displayed? -

.h

@interface viewcontroller : uiviewcontroller {   iboutlet uilabel *textview; 

}

-(ibaction)random; 

.m

-(ibaction)random{ int text = arc4random() % 24; switch (text) {     case 0:         textview.text = @"example 1";          break;      case 1:         textview.text = @"example 2";          break;      case 2:         textview.text = @"example 3";          break;      case 3:         textview.text = @"example 4";          break;      case 4:         textview.text = @"example 5";          break;      case 5:         textview.text = @"example 6";          break;      case 6:         textview.text = @"example 7";          break; 

etc... want not repeat example 1, 3,6,2,5,4,7 or , start on without repeating same thing twice unless texts have been displayed in advance