Array of UIButtons, can't change button image - objective-c

Question

I have an array of UIButton objects (I have 15 buttons so I wanted to store them in an array for easy processing). I want to be able to iterate through the array and change the background image/image that the button uses. This is how I currently have it set up:
#property (nonatomic, weak) UIImage *greenLight;
#property (nonatomic, weak) UIImage *yellowLight;
#property (nonatomic, weak) UIImage *redLight;
#property (weak, nonatomic) IBOutlet UIButton *task1Button;
#property (weak, nonatomic) IBOutlet UIButton *task2Button;
#property (weak, nonatomic) IBOutlet UIButton *task3Button;
#property (nonatomic, copy) NSMutableArray *buttonArray;
- (instancetype)init
{
self = [super init];
if(self){
[self.buttonArray addObject:self.task1Button];
[self.buttonArray addObject:self.task2Button];
[self.buttonArray addObject:self.task3Button];
self.greenLight = [UIImage imageNamed:#"greenlight.ICO"];
self.yellowLight = [UIImage imageNamed:#"yellowlight.ICO"];
self.redLight = [UIImage imageNamed:#"redlight.ICO"];
NSLog(#"init complete...");
}
return self;
}
Then I have the following in viewWillAppear
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[self.task1Button setImage:self.redLight forState:UIControlStateNormal];
[(UIButton *)self.buttonArray[1] setImage:self.greenLight forState:UIControlStateNormal];
}
The second line in viewWillAppear works and changes the button's image. The third line, however, does not. The debugger shows the code reaching that line and not throwing any errors, so I don't know why setting the button image when the button is in an array would not work.
Any ideas?

Answer 1

Try replacing last line in your answer with this :
[(UIButton *)[self.buttonArray objectAtIndex:1] setImage:self.greenLight forState:UIControlStateNormal];
But i'm doing this without compiler so i'm not really sure about where to place the first bracket [
Tell me if it works, i'm not totally sure about it.