Xcode约束？

Question

I am trying to understand and work with the constraint feature for Xcode. I can see how it can be really useful if you are a few views, since you can really specify how each one should align itself.

However, if you have a lot of views this becomes a tedious task, especially if you start messing with them programmatically (like moving them). For example the below image:

I want it to look like this when i expand and shrink the screen, but alas, it does not. Also, since they are constantly aligning to be next to each other, if i move one programmatically (like i'm making a game), the other will unintentionally move with it.

So basically, how on earth am i supposed to work with constraints when featuring quite a bit of view objects on screen + moving them in the code? Any tips are greatly appreciated! (and yes, i have tried adding / removing constraints for every single view one at a time, and firstly, it's a tedious task, and secondly, it keeps adding constraints for the views to align them with each other, and you rarely want that in a game where you move them).

thanks on advance!

Answer 1

You could try to update the constraints instead of removing and adding them all the time. You can create IBOutlets for all the constraints you need to change and then you can update them by changing the constant value

[self.heightConstraint setConstant:newValue];

Then you need to call [self layoutIfNeeded] , probably in an animation block, to see the changes after updating the constraints:

[UIView animateWithDuration:0.5 animations:^{
    [self layoutIfNeeded];
}];

I don't really know the details of your application, but maybe if you think about the constraints from the perspective of how the views relate to each other, maybe moving them would not be so difficult.

Another idea would be to group the views together in an UIView subclass. Maybe something like RowView that has the 3 images and handles the constraints just for those.

What I mean is something like "Divide and Conquer", not handling all the constraints in one view, but group them together, in a way that makes sense for you application.

Hope this helps! Good luck with your project.