使用autolayout的NSLayoutConstraint類中的constraintWithItem 、constraintsWithVisualFormat這兩個類方法來建立視圖並能夠實現自動布

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    [self createViewWithConstraintItem];
    [self createViewWithConstraint];
}

- (void)createViewWithConstraintItem
{
    UIView *redView = [[UIView alloc]init];
    redView.backgroundColor=[UIColor redColor];
    redView.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:redView];
    
    /**左邊距50*/
    NSLayoutConstraint *viewLeftConstraint = [NSLayoutConstraint constraintWithItem:redView
                                                            attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.view
                                                            attribute:NSLayoutAttributeLeading multiplier:1 constant:50.f];
    /**上邊距50*/
    NSLayoutConstraint *viewTopConstraint = [NSLayoutConstraint constraintWithItem:redView
                                                    attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view
                                                            attribute:NSLayoutAttributeTop multiplier:1 constant:100.f];
    
    /*--------------------------------------------------------------------------------
     注意：一般在設置寬度高度的時候最好不要固定死，另外當viw1.attribute不等於view2.attribute*multiplier
     +constant的時候，咱們則要constraintWithItem函數中的toItem設置爲nil以及attribute參數設置
     爲NSLayoutAttributeNotAnAttribute
     ---------------------------------------------------------------------------------*/
    /**寬度150*/
    NSLayoutConstraint *viewWidthConstaint = [NSLayoutConstraint constraintWithItem:redView
                                                            attribute:NSLayoutAttributeWidth
                                                    relatedBy:NSLayoutRelationGreaterThanOrEqual
                                                            toItem:nil
                                                        attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:150];
    /**高度150*/
    NSLayoutConstraint *viewHeightConstaint = [NSLayoutConstraint constraintWithItem:redView
                                                                attribute:NSLayoutAttributeHeight
                                                    relatedBy:NSLayoutRelationGreaterThanOrEqual
                                                                toItem:nil
                                                        attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:150];
    
    [self.view addConstraints:@[viewLeftConstraint,viewTopConstraint,viewWidthConstaint,viewHeightConstaint]];
}

- (void)createViewWithConstraint
{
    /**建立左邊view*/
    UIView *leftView = [[UIView alloc]init];
    leftView.backgroundColor = [UIColor redColor];
    leftView.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:leftView];
    
    /**建立右邊view*/
    UIView *rightView = [[UIView alloc]init];
    rightView.backgroundColor = [UIColor blueColor];
    rightView.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:rightView];
    
    
    /**建立右下方view*/
    UIView *rightBottomView = [[UIView alloc]init];
    rightBottomView.backgroundColor = [UIColor yellowColor];
    rightBottomView.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:rightBottomView];
    
    NSDictionary *viewDic = NSDictionaryOfVariableBindings(leftView,rightView,rightBottomView);
    
    /*距父視圖左邊距50以及自身寬度大於等於150*/
    NSArray *leftView_H = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-50-[leftView(>=150)]" options:0 metrics:nil views:viewDic];

    /*距父視圖上邊距100以及自身高度大於等於150*/
     NSArray *leftView_V = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[leftView(>=150)]" options:0 metrics:nil views:viewDic];

    /*水平方向佈局，rightView 在 leftView 右側標準距離處，而且寬度不小於 50 點。*/
    NSArray *rightView_H = [NSLayoutConstraint constraintsWithVisualFormat:@"H:[leftView]-[rightView(>=50)]" options:0 metrics:nil views:viewDic];
    
    NSArray *rightView_V = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[rightView(>=50)]" options:0 metrics:nil views:viewDic];
    
    
    
    NSArray *rightBottomView_H = [NSLayoutConstraint constraintsWithVisualFormat:@"H:[leftView]-[rightBottomView(>=50)]" options:0 metrics:nil views:viewDic];
    
    /*垂直方向佈局距離父視圖100，另外rightBottomView 在 rightView下方也就是至關於緊貼*/
    NSArray *rightBottomView_V = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[rightView(>=50)][rightBottomView(>=100)]" options:0 metrics:nil views:viewDic];
    
    
    [self.view addConstraints:leftView_H];
    [self.view addConstraints:leftView_V];
    
    [self.view addConstraints:rightView_H];
    [self.view addConstraints:rightView_V];
    
    [self.view addConstraints:rightBottomView_H];
    [self.view addConstraints:rightBottomView_V];
    
}

@end