ios . -- UICollectionView --cell 自适应

#pragma mark — 视图控制器中使用:(关键)
    layout.estimatedItemSize = CGSizeMake(WIDTH, );  // layout约束这边必须要用estimatedItemSize才能实现自适应,使用itemSzie无效

//
// 商品详情 容器 详情 cell

#import <UIKit/UIKit.h>

@interface DetailsViewCell : UICollectionViewCell
@property (nonatomic,strong) CategorizeListOfGoodsModel *goodsitemmodel;

@end

#import "DetailsViewCell.h"

@interface DetailsViewCell()

@property (nonatomic,strong) UILabel *titletxt;//标题
@property (nonatomic,strong) UILabel *pracetxt;//价格
@property (nonatomic,strong) UILabel *msaletxt;//销量

@end

@implementation DetailsViewCell

- (void)setGoodsitemmodel:(CategorizeListOfGoodsModel *)goodsitemmodel
{
    _goodsitemmodel = goodsitemmodel;
    self.titletxt.text = [NSString stringWithFormat:@"%@",goodsitemmodel.title];
    self.pracetxt.text = [NSString stringWithFormat:@"¥%@",goodsitemmodel.voucher_price];
    self.msaletxt.text = [NSString stringWithFormat:@"月销%@",goodsitemmodel.m_sale];

    [self.contentView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.top.mas_equalTo();
        make.width.mas_equalTo([UIScreen mainScreen].bounds.size.width);
        make.bottom.mas_equalTo(self.pracetxt.mas_bottom).offset();
    }];

    [self.titletxt mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(self).mas_offset();
        make.left.equalTo(self).mas_offset();
        make.right.equalTo(self).mas_offset(-);
    }];

    [self.pracetxt mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(self.titletxt.mas_bottom).mas_offset();
        make.bottom.equalTo(self).mas_offset(-);
        make.left.equalTo(self).mas_offset();
    }];

    [self.msaletxt mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(self.titletxt.mas_bottom).mas_offset();
        make.bottom.equalTo(self).mas_offset(-);
        make.right.equalTo(self).mas_offset(-);
    }];

}

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

- (void)initWithUIFrame:(CGRect)rect
{
    self.contentView.backgroundColor = [UIColor whiteColor];
    self.titletxt = [[UILabel alloc]init];
    self.titletxt.font = [UIFont systemFontOfSize:];
    self.titletxt.textColor = [YColor YColorWithHexString:@"#333333"];
    self.titletxt.numberOfLines = ;
    [self.contentView addSubview:self.titletxt];

    self.pracetxt = [[UILabel alloc]init];
    self.pracetxt.font = [UIFont systemFontOfSize:];
    self.pracetxt.textColor = [YColor YColorWithHexString:@"#F32F19"];
    [self.contentView addSubview:self.pracetxt];

    self.msaletxt = [[UILabel alloc]init];
    self.msaletxt.font = [UIFont systemFontOfSize:];
    self.msaletxt.textColor = [YColor YColorWithHexString:@"#999999"];
    [self.contentView addSubview:self.msaletxt];

}

#pragma mark — 实现自适应文字宽度的关键步骤:item的layoutAttributes
- (UICollectionViewLayoutAttributes*)preferredLayoutAttributesFittingAttributes:(UICollectionViewLayoutAttributes*)layoutAttributes {
    [self setNeedsLayout];
    [self layoutIfNeeded];
    CGSize size = [self.contentView systemLayoutSizeFittingSize: layoutAttributes.size];
    CGRect cellFrame = layoutAttributes.frame;
    cellFrame.size.height= size.height;
    layoutAttributes.frame= cellFrame;
    return layoutAttributes;
}

@end