With pure code to facilitate the realization AutoLayout technology to improve the efficiency of writing UI.

• AutoLayout/
• • AutoLayoutDemo/ (example)
• • src/ (source code)

1. Drag src directory to your project folder.

1. Import "UIView+AutoLayout.h" and "NSLayoutConstraint+VisualFormat" where you will use autolayout to build your interface.

2. Create UIView's subclass in your ViewController's and than apply autolayout. As follows :

    self.view.backgroundColor = [UIColor whiteColor];
    _redView = [[UIView alloc] init];
    _redView.backgroundColor = [UIColor redColor];
    [_redView setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.view addSubview:_redView];
   
    _blueView = [[UIView alloc] init];
    _blueView.backgroundColor = [UIColor blueColor];
    [_blueView setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.view addSubview:_blueView];
    
    [_redView constraintWidth:50];
    [_redView constraintHeight:50];
    [_redView centerHorizontallyToView:self.view];
    [_redView centerVerticallyToView:self.view];
   
    [_blueView constraintWidth:20];
    [_blueView constraintHeight:20];
    [_blueView centerHorizontallyToView:self.view];
    [_blueView constraintToBottomOfView:_redView withPadding:20];