This library is a category on NSLayoutConstraint that adds a few helpful methods for generating auto layout constraints. Reasons for creating this category are:

1. to have a convenient way for defining size of the component or margins to its container
2. generate constraints for tedious cases like many views with the same width or height and same space between each other

The category can create constraints to define:

1. view size
2. margins to its superview
3. layout for a set of views placed next to each other (horizontally or vertically) with the same width/height and same space in between

Each method returns an array of constraints which can be applied to the view or used for further modifications while you create your desired set of constraints.

Documentation

Below a short description of the public interface can be found.

Constants

Constant representing undefined value:

static const CGFloat kTFNoMetric = NAN;

Centering

Method returning array of constraints which will center a view passed in view argument relatively to a view passed in the superview argument

view - a view for which centring constraints will be generated

superview - a view to which view passed in the first argument will be centered

option - argument defining exactly how the view will be centered:

1. TFCenteringOptionNone - will cause in returning an empty array of constraints
2. TFCenteringOptionAxisX - will center view only on the X axis
3. TFCenteringOptionAxisY - will center view only on the Y axis
4. TFCenteringOptionAbsolute - will center view on X and Y axis

offset - CGPoint representing vector by which center of a centering view will be translated relatively to the center of the superview

Returns array of NSLayoutConstraint objects which are generated constraints, can return an empty array

+ (NSArray *)tf_centeringConstraintsForView:(UIView *)view 
                             relativeToView:(UIView *)superview 
                                    options:(TFCenteringOption)option 
                                     offset:(CGPoint)offset

Horizontal aligning

+ (NSArray *)tf_horizontalAlignmentConstraintsForViews:(NSArray *)viewsArray 
                                        separatorViews:(NSArray *)separatorsViewsArray 
                                               margins:(CGFloat)margin;

Above method returns constraints for views passed in viewsArray separated by objects in separatorsViewsArray. Moreover margins from left and right edges of a superview can be passed in margin argument. Both arrays can not be nil and number of separators can be less by 1 than number of views passed in viewsArray argument.

viewsArray - array containing UIViews for which horizontal aligning constraints will be generated

separatorsViewsArray - array containing UIViews which are separators between views for which alignment constraints will be generated

margin - CGFloat value representing (left and right) margins from the superview's edges

Returns array of NSLayoutConstraint objects which are generated constraints

Vertical aligning

+ (NSArray *)tf_verticalAlignmentConstraintsForViews:(NSArray *)viewsArray 
                                      separatorViews:(NSArray *)separatorsViewsArray 
                                             margins:(CGFloat)margin;  

Above method returns constraints for views passed in viewsArray separated by objects in separatorsViewsArray. Moreover margins from top and bottom edges of a superview can be passed in margin argument. Both arrays can not be nil and number of separators can be less by 1 than number of views passed in viewsArray argument.

viewsArray - array containing UIViews for which vertical aligning constraints will be generated

separatorsViewsArray - array containing UIViews which are separators between views for which alignment constraints will be generated

margin - CGFloat value representing (top and bottom) margins from the superview's edges

Returns array of NSLayoutConstraint objects which are generated constraints

Margins to superview

+ (NSArray *)tf_constraintsForView:(UIView *)view expandingEdgesToSuperviewWithInsets:(UIEdgeInsets)insets;

Above method returns array of constraints which adopt view to the superview size with defined in insets argument margins from each edge. If value passed as one of the insets value is kTFNoMetric then this value for margin is omitted.

view - UIView for which array of constraints will be generated and then returned

insets - UIEdgeInsets struct containing margins to each superview's edge if kTFNoMetric set then this margin is not defined

Returns array of NSLayoutConstraint objects which are generated constraints for a passed view

Size setting

+ (NSArray *)tf_constraintsForView:(UIView *)view withSize:(CGSize)size;

Above method returns array of width and/or height constraints for a view passed in view argument if one of the value is set to kTFNoMetric then constraint generation will be omitted for that metric.

view - UIView for which array of constraints will be generated and then returned

size - CGSize struct defining width and height to set in a constraint for a view

Returns array of NSLayoutConstraint objects which are generated constraints for a passed view

Installation

Usage

To run the example project, clone the repo, and run pod install from the Example directory first.

Examples

The example below will return constraints for a view defining its height. Width setting will be ommitted because of kTFNoMetric value.

[NSLayoutConstraint tf_constraintsForView:view withSize:CGSizeMake(kTFNoMetric, 80)];

The example below will return an array of constraints for view. In the following example constraints will set margins from the superview: 10 points from top, 20 from left, margin to bottom will be unspecified and finally 40 from right.

[NSLayoutConstraint tf_constraintsForView:view expandingEdgesToSuperviewWithInsets:UIEdgeInsetsMake(10, 20, kTFNoMetric, 40)];

The example below will return ans array of constraints for view. In the presented example view will be centred on the X and Y axis according to center of the superview and translated by 120 points on the Y axis.

[NSLayoutConstraint tf_centeringConstraintsForView:view relativeToView:superview options:TFCenteringOptionAbsolute offset:CGPointMake(kTFNoMetric, 120)];

The code below will return array of constraints for aligning views passed in viewsArray separated by objects in separatorsArray. Returned constraints will set width of all views to be equal between them and the space between them will be also equal to each other. Margin from left and right will be set to 15 points.

[NSLayoutConstraint tf_horizontalAlignmentConstraintsForViews:viewsArray separatorViews:separatorsArray margins:15]

In the example below returned constraints will act analogously to the previous example but in the vertical way. This means that margins from top and bottom edge of the superview will be set to 15 points, views passed in viewsArray will have the same height. Spaces between as previously - equal.

[NSLayoutConstraint tf_verticalAlignmentConstraintsForViews:viewsArray separatorViews:separatorsArray margins:15]

Changelog

1.1.0

• Added method for centering constraints generation
• Added TFLogger support

1.0.1

• Clarifications in the documentation

1.0.0

• Initial release

Author

Julian Król, [email protected]

(In case of any bugs or ideas for extension, feel free to drop me an email)

License

TFLayoutConstraintsFactory is available under the Apache 2.0 license. See the LICENSE file for more info.