Create array of UILabels in Xcode

Question

I am trying to streamline a little project that I am working on where I have eight UILabels, and every so often I have the background color of these labels change to a different color based on data stored in an array.

Currently my code runs a for loop from 0 to 7 (to account for the eight UILabels). Within the for loop, it will check what number the for loop is upto and amend the corresponding UILabel with the new background color, like this:

for (int y = 0; y < 8; y++) {
    SEL mySelect = NSSelectorFromString([backgroundColorData objectAtIndex:y]);
    UIColor* myUILabelColor = nil;
    if ([UIColor respondsToSelector: mySelect]){
        myUILabelColor = [UIColor performSelector:mySelect]; 
    } 
    switch (y) {
            Label0.backgroundColor = myUILabelColor;
            break;
        case 1:
            Label1.backgroundColor = myUILabelColor;
            break;
        case 2:
            Label2.backgroundColor = myUILabelColor;
            break;
        case 3:
            Label3.backgroundColor = myUILabelColor;
            break;
        case 4:
            Label4.backgroundColor = myUILabelColor;
            break;
        case 5:
            Label5.backgroundColor = myUILabelColor;
            break;
        case 6:
            Label6.backgroundColor = myUILabelColor;
            break;
        case 7:
            Label7.backgroundColor = myUILabelColor;
            break;
    }

I would like to be able to make the code scaled down by placing these 8 UILabels into an array and perhaps making the code read as follows:

 for (int y = 0; y < 8; y++) {
     SEL mySelect = NSSelectorFromString([backgroundColorData objectAtIndex:y]);
     UIColor* myUILabelColor = nil;
     if ([UIColor respondsToSelector: mySelect]){
         myUILabelColor = [UIColor performSelector:mySelect]; 
     } 
     // This piece of code would deal with modifying the backgroundColor of UILabel(y) within my array of UILabels.
 }

Or now that I think about it, perhaps I could do it all in one big hit whereby I don't need to run through a for loop eight times, but I could just directly send the contents of my backgroundcolordata array into my UILabel array?

Any help or tips here would be very much appreciated.

You don't need backquotes around code blocks. You should, however, indent them properly. — Marcelo Cantos
– Marcelo Cantos, Commented Dec 7, 2011 at 12:19
Thankyou fluchtpunkt for fixing up the formatting of my code. I thought I was doing it correctly by indenting by four spaces but it did not come out correctly. — BradSlattery
– BradSlattery, Commented Dec 7, 2011 at 12:26
What's wrong with simply storing your labels in an NSArray that you create once at initialization? — Vladimir Gritsenko
– Vladimir Gritsenko, Commented Dec 7, 2011 at 12:50
I have been trying to create an array of labels although haven't been successful so far. Will keep experimenting though. — BradSlattery
– BradSlattery, Commented Dec 7, 2011 at 13:31

Rob Napier · Accepted Answer · 2011-12-07 13:57:54Z

3

First, I would just store actual UIColor objects in backgroundColorData rather than names of colors. Then store the UILabel objects in an array. Then the entire code looks like this:

NSUInteger count = [self.labels count];
for (NSUInteger index = 0; index < count; ++index) {
    UIColor *color = [self.backgroundColors objectAtIndex:index];
    [[self.labels objectAtIndex:index] setBackgroundColor:color];
}

answered Dec 7, 2011 at 13:57

Rob Napier

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2 Comments

BradSlattery Over a year ago

Thankyou very much for that, will test it out on my lunch break!

BradSlattery Over a year ago

Once again, thankyou this code worked perfectly (once I worked out how to add my UILabels into my array).

tarmes · Accepted Answer · 2011-12-07 14:06:37Z

3

You can get the label by name, which can be a useful technique sometimes:

NSString *name = [NSString stringWithFormat:@"Label%d", y];
UILabel *label = [self valueForKey:name];
backgroundColor = myUILabelColor = name;

P.S. Instances should really start with a lower case letter. i.e. 'label1', not 'Label1'.

answered Dec 7, 2011 at 14:06

tarmes

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