Overview

UIView+FDCollapsibleConstraints builds to collapse a view and its relevant layout constraints, simulating a "Flow Layout" mode.

Demo 1

This demo collapses the forkingdog image view and its bottom margin constraint.

Demo 2

This demo collapses diffent components in cell, according to its data entity, each margin handles right as well.

Basic usage

1. Select constraints to collapse

First, tell which constraints will be collapsed when the view collapses. We provide a IBOutletCollection to make it easier in Interface Builder:

@property (nonatomic, copy) IBOutletCollection(NSLayoutConstraint) NSArray *fd_collapsibleConstraints;

You can assgin it by codes, but it's better to "connect lines" in Interface Builder:

2. Collapse a view

Selected constraints will collapse when:

view.fd_collapsed = YES;

And expand back when:

view.fd_collapsed = NO;

Auto collapse

Not every view needs to add a width or height constraint, views like UILabel, UIImageView have their Intrinsic content size when they have content in it. For these views, we provide a Auto collapse property, when its content is gone, selected constraints will collapse automatically.
You can enable auto collapse by:

label.fd_autoCollapse = YES;
imageView.fd_autoCollapse = YES;

And it will work as you expect:

label.text = nil/*or @""*/; (auto => label.fd_collapsed = YES)
label.text = @"forkingdog"; (auto => label.fd_collapsed = NO)
imageView.image = nil; (auto => imageView.fd_collapsed = YES)
imageView.image = [UIImage imageNamed:@"forkingdog"]; (auto => imageView.fd_collapsed = NO)

We've also offered a Interface Builder friendly way to enable auto collapse:

@property (nonatomic, assign, getter=fd_autoCollapse) IBInspectable BOOL autoCollapse;

Here's what you may find in Attribute Inspector

It's behavior is same as setting fd_autoCollapse property in code.

Installation

Cocoapods:

pod search UIView+FDCollapsibleConstraints

License

MIT