Random color for custom view that cannot be reused

Question

I have a custom view, which is a circle view. The view has a custom UIColor randomColor background from another method.

Issue - What I am trying to do is only have the color used once. In this case I have three circle views and 6 colors. So I am looking for one color (randomly selected) for each of the three circle views. What is the best way to accomplish?

-(void)setupView {
    self.translatesAutoresizingMaskIntoConstraints = NO;
    float newRadius = self.frame.size.width/2;
    self.layer.cornerRadius = newRadius; 
    self.layer.masksToBounds= YES;

    self.layer.borderWidth = 5;
    self.layer.borderColor = [UIColor colorWithRed:0.138 green:0.225 blue:1.000 alpha:1.000].CGColor;


    self.backgroundColor = [self randomColor];

    [self setupLabel];
}


-(UIColor *)randomColor {
    static NSArray *__colors = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        __colors = @[
                     [UIColor colorWithRed:.11372549  green:.819607843 blue:.819607843 alpha:1.0], //29,209,99
                     [UIColor colorWithRed:.882352941 green:.466666667 blue:.709803922 alpha:1.0], //225,119,181
                     [UIColor colorWithRed:.647058824 green:.164705882 blue:.482352941 alpha:1.0], //165,42,123
                     [UIColor colorWithRed:.482352941 green:.17254902  blue:.733333333 alpha:1.0], //123,44,187
                     [UIColor colorWithRed:.219607843 green:.098039216 blue:.698039216 alpha:1.0], //56,25,178
                     [UIColor colorWithRed:.678431373 green:.843137255 blue:.274509804 alpha:1.0]  //173,215,70
                     ];
    });
    int index = arc4random_uniform((uint32_t)__colors.count);
    return __colors[index];
}

@StuartM: Validate, yes, in its form, information given, clear question, etc. But seems like a duplicate. That may explain some down votes. — Larme, May 07 '14 at 14:29
I think that you are voted down because your question is very similar to topic that commented above. — Vlad Papko, May 07 '14 at 14:29
but this is very different, this is a View not a View Controller so I cannot create the starting array in viewDidLoad. Also they should vote to close not vote down. — StuartM, May 07 '14 at 14:35
@StuartM I've posted possible solution for your issue. Please check it. — Vlad Papko, May 07 '14 at 14:44
The duplicate explains how to get a unique random item out of an array. If you are unsure of where to initialize the array, that's really a separate issue and should be researched separately and posted as its own question should your research arrive at a dead end. — Carl Veazey, May 08 '14 at 03:48

score 2 · Accepted Answer · answered May 07 '14 at 14:43

Okey, If you want to avoid duplication you need remove color from array if it selected.
Try this:

-(UIColor *)randomColor {
    static NSMutableArray *__colors = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        __colors = [NSMutableArray arrayWithArray:@[[UIColor colorWithRed:.11372549  green:.819607843 blue:.819607843 alpha:1.0], //29,209,99
                                                    [UIColor colorWithRed:.882352941 green:.466666667 blue:.709803922 alpha:1.0], //225,119,181
                                                    [UIColor colorWithRed:.647058824 green:.164705882 blue:.482352941 alpha:1.0], //165,42,123
                                                    [UIColor colorWithRed:.482352941 green:.17254902  blue:.733333333 alpha:1.0], //123,44,187
                                                    [UIColor colorWithRed:.219607843 green:.098039216 blue:.698039216 alpha:1.0], //56,25,178
                                                    [UIColor colorWithRed:.678431373 green:.843137255 blue:.274509804 alpha:1.0]  //173,215,70
                                                    ]];
    });
    int index = arc4random_uniform((uint32_t)__colors.count);

    UIColor *color = __colors[index];
    [__colors removeObjectAtIndex:index];
    return color;
}

Great thanks, now I understand makes a lot of sense when you can read it — StuartM, May 07 '14 at 14:49

score 1 · Answer 2 · answered May 07 '14 at 14:10

1

try to hold colours in NSMutableArray, and if you use this colour then delete it from array:

[mutableArray removeObject:color];

answered May 07 '14 at 14:10

Nazariy Vlizlo

778
7
16

Exactly what I was going to suggest. (voted) – Duncan C May 07 '14 at 14:14
At what point would you suggest to remove the object? – StuartM May 07 '14 at 14:21
from the documentation: Removes all occurrences in the array of a given object. – Nazariy Vlizlo May 07 '14 at 14:24
Is it as simple as after I have used it. I have checked the example link in the comments but it is different this is a View class not a view controller so I do not create the objects in viewDidLoad. In terms of my example code in the question, where would I create a mutableCopy and remove the object please?? – StuartM May 07 '14 at 14:40
I cannot remove in the method before it is returned... – StuartM May 07 '14 at 14:41
create mutableArray like property in your Controller and make some method with removeObject – Nazariy Vlizlo May 07 '14 at 14:43
It is not controlled by the controller this is a storyboard- uiview class, it has been answered correctly above. Thanks – StuartM May 07 '14 at 14:50

Random color for custom view that cannot be reused

2 Answers2