如何在同一视图控制器（iOS）中将具有相同元素的不同UI应用于？

Question

I'm using Swift in Xcode 7 with Storyboard. I have different UI with same elements in same view controller. Depending on the data fetched from server, I wish to display different UI layout.

To make it easier to understand, eg I have one view controller with one label aligned the bottom of the view. While data is fetched from server, I want to display the label with different layout:

• If server returns layout as bottom , I'll apply the layout of text as align bottom and centre horizontally
• If server returns layout as centre , I want to apply the layout of text as centre vertically and centre horizontally

As a result, if I have many elements, it becomes hard for me to code the NSLayoutConstraint manually. Is there anyway I can still use Interface Builder to have different UI which applied to same view controller?

Answer 1

I've had the same issue before and managed to come with a solution, though it is probably not how it was intended by apple. I tested and it works with xcode 6 and 7, possibly earlier versions too. Your question does not say if you are working with nibs or storyboards, but the answer I'm providing is for nibs. To set up your nib you need to add 2 view controllers or more.Set up your view controllers the way you need them to look and set the view controllers' main view's tag so you can differentiate them. To be able to connect your IBOutlets you will need to apply a bit of a trick:

• You set the first view controller's class so you can connect the outlets.
• You connect the outlets. You delete the class name in the attribute inspector. (Note that the outlets in the nib stay connected, but in the .m or .h file they show they are not. If you try to build your project now it will fail.)
• You set the second view controller's class so you can connect the outlets again.
• You connect the outlets again. You re-enter the class name in the attribute inspector for the first view controller.

Now you just need to get to your view controllers. For this I use a class method to get an instance of the view controller:

+ (UIViewController *)customViewControllerForLayout:(NSInteger)layoutTag
{
    NSArray *customViewControllers = [[NSBundle mainBundle] loadNibNamed:@"Your nib's name" owner:self options:nil];

    __block UIViewController *customViewControllerWithSpecifiedLayout = nil;
    [customViewControllers enumerateObjectsUsingBlock:^(UIViewController *customViewController, NSUInteger index, BOOL *stop) {
        if (customViewController.view.tag == layoutTag) {
            customViewControllerWithSpecifiedLayout = customViewController;
            *stop = YES;
        }
    }];

    return customViewControllerWithSpecifiedLayout;
}