1. 问题描述

子view有多个，宽度不一致;父view宽度需要取其最大宽度

2.代码

    UIView * bgView = [[UIView alloc] init];
    [self.view addSubview:bgView];
    bgView.backgroundColor = [UIColor whiteColor];
    
    view = [WPNewView new];
    view.backgroundColor = [UIColor greenColor];
    [bgView addSubview:view];
    
    view2 = [WPNewView new];
    view2.backgroundColor = [UIColor greenColor];
    [bgView addSubview:view2];
    
    [bgView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.centerY.equalTo(self.view);
        make.bottom.equalTo(view2).offset(10);
        make.width.mas_lessThanOrEqualTo(400);
    }];
    
    [view mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(bgView);
        make.left.equalTo(bgView).offset(10);
//        make.right.equalTo(bgView).offset(-10);
        make.height.mas_equalTo(50);
        make.width.mas_lessThanOrEqualTo(bgView).offset(-20);
    }];
    
    [view2 mas_makeConstraints:^(MASConstraintMaker *make) {
        make.height.equalTo(view);
        make.left.equalTo(bgView).offset(10);
//        make.right.equalTo(bgView).offset(-10);
        make.top.equalTo(view.mas_bottom).offset(10);
        make.width.mas_lessThanOrEqualTo(bgView);
    }];

2.2 WPNewView

#import <UIKit/UIKit.h>
@interface WPNewView : UIView
@property (strong, nonatomic) UILabel *nickLabel;
@property (strong, nonatomic) UILabel *contentLabel;
@property (strong, nonatomic) UIImageView *imageView;
@end

#import "WPNewView.h"
#import "Masonry.h"
#define UIColorFromRGBA(rgbValue, alphaValue) [UIColor \
colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 \
green:((float)((rgbValue & 0x00FF00) >> 8))/255.0 \
blue:((float)(rgbValue & 0x0000FF))/255.0 \
alpha:alphaValue]

#define UIColorFromRGB(rgbValue) UIColorFromRGBA(rgbValue, 1.0)

@implementation WPNewView

- (instancetype)init{
    self = [super init];
    if (self) {
        
        _nickLabel = [UILabel new];
        _nickLabel.font = [UIFont systemFontOfSize:14];
        _nickLabel.backgroundColor = [UIColor redColor];
        _nickLabel.textColor = UIColorFromRGB(0x333333);
        [self addSubview:_nickLabel];
        
        _contentLabel = [UILabel new];
        _contentLabel.font = [UIFont systemFontOfSize:14];
        _contentLabel.backgroundColor = [UIColor redColor];
        _contentLabel.textColor = UIColorFromRGB(0x333333);
        [self addSubview:_contentLabel];
        
        _imageView = [[UIImageView alloc] init];
        _imageView.backgroundColor = [UIColor redColor];
        [self addSubview:_imageView];
        
        self.nickLabel.text = @"--";
        self.contentLabel.text = @"--";
                
        [_nickLabel mas_makeConstraints:^(MASConstraintMaker *make) {
            make.left.equalTo(self).offset(10);
            make.top.equalTo(self).offset(6);
            make.right.equalTo(self.imageView.mas_left).offset(-10);
            make.height.mas_equalTo(17);
            make.width.mas_lessThanOrEqualTo(300);
        }];
        
        [_contentLabel mas_makeConstraints:^(MASConstraintMaker *make) {
            make.left.equalTo(self.nickLabel);
            make.top.equalTo(self.nickLabel.mas_bottom).offset(4);
            make.height.mas_equalTo(13);
            make.right.equalTo(self.imageView.mas_left).offset(-10);
        }];
        
        [_imageView mas_makeConstraints:^(MASConstraintMaker *make) {
            make.size.mas_equalTo(CGSizeMake(34, 34));
            make.centerY.equalTo(self);
            make.right.equalTo(self).offset(-10);
        }];
    }
    return self;
}

@end

小结:之前是使用layoutIfNeeds，父view然后取最大宽度，如果是tableView，性能会有问题，代码也不美观，可读性差。

参考文章:https://www.cnblogs.com/shanyimin/p/5732774.html