gebirgsbärbel gebirgsbärbel - 6 months ago 57
Objective-C Question

IBOutletCollection set ordering in Interface Builder

I am using IBOutletCollections to group several Instances of similar UI Elements. In particular I group a number of UIButtons (which are similar to buzzers in a quiz game) and a group of UILabels (which display the score). I want to make sure that the label directly over the button updates the score. I figured that it is easiest to access them by index. Unfortunately even if I add them in the same order, they do not always have the same indexes. Is there a way in Interface Builder to set the correct ordering.

Answer

EDIT: Several commenters have claimed that more recent versions of Xcode return IBOutletCollections in the order the connections are made. Others have claimed that this approach didn't work for them in storyboards. I haven't tested this myself, but if you're willing to rely on undocumented behavior, then you may find that the explicit sorting I've proposed below is no longer necessary.


Unfortunately there doesn't seem to be any way to control the order of an IBOutletCollection in IB, so you'll need to sort the array after it's been loaded based on some property of the views. You could sort the views based on their tag property, but manually setting tags in IB can be rather tedious.

Fortunately we tend to lay out our views in the order we want to access them, so it's often sufficient to sort the array based on x or y position like this:

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Order the labels based on their y position
    self.labelsArray = [self.labelsArray sortedArrayUsingComparator:^NSComparisonResult(UILabel *label1, UILabel *label2) {
        CGFloat label1Top = CGRectGetMinY(label1.frame);
        CGFloat label2Top = CGRectGetMinY(label2.frame);

        return [@(label1Top) compare:@(label2Top)];
    }];
}