UILabel in a NSMutableArray unrecognized selector - ios

Question

In my app, I have created a 'NSMutalbeArray', in which I add some 'UILabel'.
I correctly initialize my array :
_pickerMonthLabel = [[NSMutableArray alloc] init];
I correctly add UILabels in my array, but when I want to make some changes to a label, the behavior is strange. For example, I want to change the text color of a label in my array. I do :
[(UILabel *)[_pickerMonthLabel objectAtIndex:i] setTextColor:[UIColor redColor]];
This doesn't look like to work because my app crashes :
-[__NSCFConstantString setTextColor:]: unrecognized selector sent to instance 0x17e8d4
*** Terminating app due to uncaught exception
'NSInvalidArgumentException', reason: '-[__NSCFConstantString setTextColor:]: unrecognized selector sent to instance 0x17e8d4'
But i have no warning when I wrote this line. When I write another kind of line :
(UILabel *)[_pickerMonthLabel objectAtIndex:i].textcolor = [UIColor redColor];
It gives me an error :
Property 'textcolor' not found on object of type 'id'
I don't understand the difference between these two lines, and how to fix my problem...
Thank you in advance for your help.

Answer 1

I guess this is more of a remark, but you could try to use the respondsToSelector: message to check if the instance can handle the message you are trying to send. (This will make sure you don't get an exception) In your case this would be:
if ([[_pickerMonthLabel objectAtIndex:i] respondsToSelector:#selector(setTextColor:)]){
[(UILabel *)[_pickerMonthLabel objectAtIndex:i] setTextColor:[UIColor redColor]];
}
// add this to see what your class is
//else{
// NSLog(#"The class is: %#", [[_pickerMonthLabel objectAtIndex:i] class]);
//}
Hope it helps your debugging.