Parus
Parus is a small objective-c DSL for AutoLayout in code.
Features
- It is easy to create constraints - just like writing a sentence;
- More compact and semantical than usual NSAutoLayout;
- Flexibility in creating constraints - you specify only parameters that you need;
- Autocomplete rocks!
Usage
Single constraint
NSLayoutConstraint:
[NSLayoutConstraint constraintWithItem:view
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:superview
attribute:NSLayoutAttributeLeft
multiplier:2.0
constant:10];Using Parus:
PVLeftOf(view).equalTo.leftOf(superview).multipliedTo(2).plus(10).asConstraint;Using default values make it even shorter:
[NSLayoutConstraint constraintWithItem:view
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeNotAnAttribute
multiplier:1.0
constant:10];PVLeftOf(view).equalTo.constant(10).asConstraint;Visual Formatting Language (VFL)
Simple VFL constraints:
[NSLayoutConstraint constraintsWithVisualFormat:@"|-padding-[view]-padding-|"
options:(NSLayoutFormatAlignAllTop |
NSLayoutFormatDirectionLeadingToTrailing)
metrics:@{@"padding" : @20}
views:NSDictionaryOfVariableBindings(view)];PVVFL(@"|-padding-[view]-padding-|").alignAllTop.fromLeadingToTrailing.withViews(NSDictionaryOfVariableBindings(view)).metrics(@{@"padding": @20}).asArray;With special masks and defaults:
[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[view1][view2][view3]|"
options:(NSLayoutFormatAlignAllLeft |
NSLayoutFormatAlignAllRight)
metrics:nil
views:NSDictionaryOfVariableBindings(view1, view2, view3)];PVVFL(@"V:|[view1][view2][view3]|").alignAllLeftAndRight.withViews(NSDictionaryOfVariableBindings(view1, view2, view3)).asArray;Groups
There is available feature that helps you group constraints and produce even less code. Enjoy!
[someView addConstraint:[NSLayoutConstraint constraintWithItem:view
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeNotAnAttribute
multiplier:1.0
constant:10]];
[someView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[view1][view2][view3]|"
options:(NSLayoutFormatAlignAllLeft |
NSLayoutFormatAlignAllRight)
metrics:nil
views:NSDictionaryOfVariableBindings(view1, view2, view3)]];
[someView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[view1]|"
options:NSLayoutFormatDirectionLeadingToTrailing
metrics:nil
views:NSDictionaryOfVariableBindings(view1)]];[someView addConstraints:PVGroup(@[PVLeftOf(view).equalTo.constant(10),
PVVFL(@"V:|[view1][view2][view3]|").alignAllLeftAndRight,
PVVFL(@"H:|[view1]|")
]).withViews(NSDictionaryOfVariableBindings(view1, view2, view3)).asArray];You can also use usual NSLayoutConstraint or NSArray of NSLayoutConstraint as an item for PVGroup(). Following code is totally acceptable:
NSLayoutConstraint* usualConstraint = [NSLayoutConstraint constraintWithItem:... blablabla very long constraint definition ...];
NSArray* usualConstraints = [NSLayoutConstraint constraintsWithVisualFormat:... blabla ...];
[someView addConstraints:PVGroup(@[usualConstraint, usualConstraints]).asArray];Alternatives
Installation
Use cocoapods!
pod 'Parus'#import <Parus/Parus.h>TODO
- Mac OS X support;
- Extend debug description;
- Category for NSString as a start point for creating VFL.
More information
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