iOS小经验·Masonry布局时因不熟悉Cell生命周期而导致死循环

#import <UIKit/UIKit.h>

@interface DownloadCollectionFooter : UICollectionReusableView

/** 标题 */
@property (nonatomic,strong) UIButton * footerBtn;
/** 内存 */
@property (nonatomic,strong) NSString * footerStr;

@end

#import "DownloadCollectionFooter.h"
#import "Masonry.h"
@implementation DownloadCollectionFooter

- (instancetype)init
{
    self = [super init];
    if (self) {
         //...
    }
    return self;
}

- (void)layoutSubviews{
    
    [super layoutSubviews];
    _footerBtn = [[UIButton alloc]init];
    [_footerBtn setTitle:@"下载" forState:UIControlStateNormal];
    _footerBtn.titleLabel.font = [UIFont systemFontOfSize:15];
    [self addSubview:_footerBtn];
    
    [_footerBtn mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.equalTo(self.mas_left).offset(25);
        make.right.equalTo(self.mas_right).offset(-25);
        make.top.equalTo(self.mas_top).offset(7);
        make.height.mas_equalTo(@36);
    }];
}

-(instancetype)initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {
        [self initSubViews];
    }
    return self;
}

- (void)layoutSubviews{
    
    [super layoutSubviews];
    
    _titleLabel = [[UILabel alloc]init];
    [self addSubview:_titleLabel];
    _titleLabel.frame = CGRectMake(0, 7, SCREEN_WIDTH, 24);
    _titleLabel.centerX = self.centerX;
    _titleLabel.text = @"缓存";
    //等等
}