Autolayout布局模式

import “ViewController.h”

@interface ViewController ()

@end

@implementation ViewController

• (void)viewDidLoad {
  [super viewDidLoad];
  /*
  AutoLayout由来
  IOS6之后出现的一种新的布局方式，用于取代原先的Autosizing系统的布局方式
  Autolayout是指定视图和其父视图或者视图和其兄弟之间的关系来布局
  在Autolayout当中，我们使用约束来描述视图和视图之间的关系
  Oc专门为开发者封装了一个类NSlayoutConstraint来帮助开发者描述布局

  */

  /*
  参数的意义
  1，（id）item:约束中的两个视图对象
  2，attribute:描述视图的对齐特征
  3,relateBy:描述两个视图attribute的关系
  4，multiplier：缩放比例
  5，constant:偏移量

  视图1.属性 关系 视图2.属性*缩放比例+偏移量

  视图1.左边 ==视图2.左边*1+0；
  [NSLayoutConstraint constraintWithItem:view1 attribute:左边 relatedBy:== toItem:view2 attribute:左边 multiplier:1 constant:0]
  视图1.宽度 ==100
  [NSLayoutConstraint constraintWithItem:view1 attribute:宽度 relatedBy:== toItem:nil attribute:nil multiplier:0 constant:100]

  */
  //
  // UIView *view1 = [UIView new];
  // UIView *view2 = [UIView new];
  // UIView *view3 = [UIView new];
  // //启用Autolayout布局方式
  // view1.translatesAutoresizingMaskIntoConstraints = NO;
  // view1.backgroundColor = [UIColor greenColor];
  // view2.translatesAutoresizingMaskIntoConstraints = NO;
  // view2.backgroundColor = [UIColor redColor];
  //
  // NSLayoutConstraint *constraint1 = [NSLayoutConstraint constraintWithItem:view1 attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeRight multiplier:1 constant:10];
  // NSLayoutConstraint *constraint2 = [NSLayoutConstraint constraintWithItem:view2 attribute: NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeRight multiplier:1 constant:20];
  //
  //
  //
  // [self.view addConstraint:constraint1];
  //
  //
  //
  // [self.view addConstraint:constraint2];

  UIView *view1 = [UIView new ];
  view1.translatesAutoresizingMaskIntoConstraints = NO;
  view1.backgroundColor = [UIColor redColor];
  [self.view addSubview:view1];
  NSLayoutConstraint *constraint1 = [NSLayoutConstraint constraintWithItem:view1 attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1 constant:0];
  NSLayoutConstraint *constraint2 = [NSLayoutConstraint constraintWithItem:view1 attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterY multiplier:1 constant:0];
  NSLayoutConstraint *constraint3 = [NSLayoutConstraint constraintWithItem:view1 attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:100];
  NSLayoutConstraint *constraint4 = [NSLayoutConstraint constraintWithItem:view1 attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:100];
  [self.view addConstraint:constraint1];
  [self.view addConstraint:constraint2];
  [self.view addConstraint:constraint3];
  [self.view addConstraint:constraint4];
  

}

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

@end