Changing the random image - objective-c

Question

With the help of a few threads here I created a slideshow that starts as soon as my view loads
However I am trying to make a slight modification where, I want the images to be random Not showing in the order in the array or in any particular order. This is my codde
-(void)viewDidAppear:(BOOL)animated
{
NSArray *myImages=[NSArray arrayWithObjects:
[UIImage imageNamed:#"Pitt Bull"],
[UIImage imageNamed:#"German Sherpard"],
[UIImage imageNamed:#"Pincer"],
nil];
int indexed=arc4random()%[myImages count];
UIImage *image=[myImages objectAtIndex:indexed];
NSArray *imageAr=[NSArray arrayWithObject:image];
[NSTimer scheduledTimerWithTimeInterval:12.0
target:self
selector:#selector(viewDidAppear:)
userInfo:Nil
repeats:YES];
[self.kenView animageWithImages:imageAr
transitionDuration:12
loop:YES
isLandscape:YES];
}
However it only works once. it loads a random picture at the start, but after that it keeps loading the same image. I can see that is because indexed is only assigned an integer when the view "did appear" . I was wondering if there was another way too select a new random number since I am not using a button/action as I saw many of other members doing. OR a better way of accomplishing this.
Thank you

Answer 1

You may want to try this function, + (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)seconds target:(id)target selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)repeats from NSTimer.
For example, in ViewDidLoad
timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(showImage:) userInfo:nil repeats:YES];
and declare a function
- (void)showImage:(NSTimer*)timer
{
// your code to generate random index and animate image transition
}
if for some reason, you want to stop the timer
[timer invalidate];
Update
To avoid the timer messing up issue, trigger timer inside showImage, in ViewDidLoad, do [self showImage]
- (void)showImage
{
// your code to generate random index and animate image transition
// trigger the timer when the transition is finished
// You can leverage the method animateWithDuration:animations:completion:
// from UIView
[UIView animateWithDuration:12
animations:^(){
// image transition
}
completion:^(BOOL finished){
timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(showImage) userInfo:nil repeats:NO];
}]
}
This should provide you the idea.

Answer 2

Consider using this method to randomly shuffle the elements of your array at startup.