CATLayout

Objective-C Auto Layout Constraint Builder with Chaining Pattern

Why do We Need a Constraint Builder ?

It's simply because that we will never like the codes below:

[NSLayoutConstraint constraintWithItem:fromItem
							 attribute:fromAttribute
						     relatedBy:relation
								toItem:toItem
							 attribute:toAttribute
							multiplier:multiplier
						      constant:constant]

Builder and Syntax

1. CATLayout from -[UIView cat_layout]

syntax: <#from attribute#>.<#relation#>.<#multiplier#>.<#to attribute of view#>.<#constant#>

example: view.cat_layout.width.equal.multiply(0.5f).widthOf(container).constant(8)

2. CATPin from -[UIView cat_pin]

syntax: <#width or height#>.<#relation#>.<#multiplier#>.<#to/than view#>.<#constant#>

example: view.cat_pin.height.to(container).constant(-16)

3. CATAlign from -[UIView cat_align]

syntax: <#attribute#>.<#relation#>.<#to/than view#>.<#constant#>

example: view.cat_align.left.to(container).constant(8)

Much like natural language, isn't it?

Other Features

Easy to Create and Add the Constraint

All these builder classes support 3 ways to build the constraint:

1. - (NSLayoutConstraint *)constraint;

create and return the constraint

2. - (NSLayoutConstraint *)setInView:(UIView *)container;

create and add the constraint to container view

3. - (NSLayoutConstraint *)set;

create and add the constraint to the nearest common ancestor of fromView and toView

Copying and Reverse Supported

You could use -reverse method to avoid some constraint conflict.

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Check out the project to run the demo. Keep constraints simple. Have fun!