IOS autolayout code snippet

ViewController.m

//
//  ViewController.m
//  AutoLayoutDemo
//
//  Created by Ting Sun on 6/17/15.
//  Copyright (c) 2015 sunting. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic, strong) UIView *redView;
@property (nonatomic, strong) UIView *yellowView;

@end

@implementation ViewController

- (void)viewDidLoad {
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.
  
  self.redView = [UIView new];
  self.redView.translatesAutoresizingMaskIntoConstraints = NO;
  self.redView.backgroundColor = [UIColor colorWithRed:0.95 green:0.47 blue:0.48 alpha:1.0];
  
  self.yellowView = [UIView new];
  self.yellowView.translatesAutoresizingMaskIntoConstraints = NO;
  self.yellowView.backgroundColor = [UIColor colorWithRed:1.00 green:0.83 blue:0.58 alpha:1.0];
  
  [self.view addSubview:self.redView];
  [self.view addSubview:self.yellowView];
  
  NSDictionary *viewsDictionary = @{@"redView":self.redView, @"yellowView":self.yellowView};
  
  NSArray *constraint_V = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[redView(50)]"
                                                                  options:0
                                                                  metrics:nil
                                                                    views:viewsDictionary];
  
  NSArray *constraint_H = [NSLayoutConstraint constraintsWithVisualFormat:@"H:[redView(100)]"
                                                                  options:0
                                                                  metrics:nil
                                                                    views:viewsDictionary];
  
  [self.redView addConstraints:constraint_H];
  [self.redView addConstraints:constraint_V];
  
  NSArray *constraint_POS_V = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-30-[redView]"
                                                                      options:0
                                                                      metrics:nil
                                                                        views:viewsDictionary];
  
  NSArray *constraint_POS_H = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-20-[redView]"
                                                                      options:0
                                                                      metrics:nil
                                                                        views:viewsDictionary];
  [self.view addConstraints:constraint_POS_V];
  [self.view addConstraints:constraint_POS_H];
  
  NSArray *yellow_constraint_H = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[yellowView(200)]"
                                                                         options:0
                                                                         metrics:nil
                                                                           views:viewsDictionary];
  
  NSArray *yellow_constraint_V = [NSLayoutConstraint constraintsWithVisualFormat:@"H:[yellowView(100)]"
                                                                         options:0
                                                                         metrics:nil
                                                                           views:viewsDictionary];
  [self.yellowView addConstraints:yellow_constraint_H];
  [self.yellowView addConstraints:yellow_constraint_V];
  
  constraint_POS_H = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-20-[redView]-10-[yellowView]"
                                                                      options:0
                                                                      metrics:nil
                                                                      views:viewsDictionary];
  
  [self.view addConstraints:constraint_POS_H];
}

- (void)didReceiveMemoryWarning {
  [super didReceiveMemoryWarning];
  // Dispose of any resources that can be recreated.
}

@end