标准MVC下生成动态生成UICollectionViewCell

上篇文章说明了标准MVC下如何动态生成标准MVC下生成动态生成UICollectionViewCell的size，并且在此部分工作由View完成。连接如下：

这篇文章主要说明的是如何在Controller实现这部分功能。
效果图如下（跟之前没什么区别）

同样自定义UICollectionViewCell:

#import <UIKit/UIKit.h>

@interface LCHCollectionViewCell : UICollectionViewCell

@property (nonatomic, strong) UILabel *firstLabel;

@property (nonatomic, strong) UILabel *secondLabel;

@end

然后重写其initWithFrame方法，用于将label加到其contentView中去：

@implementation LCHCollectionViewCell

- (id)initWithFrame:(CGRect)frame {
    
    self = [super initWithFrame:frame];
    if (self) {
        
        _firstLabel = [[UILabel alloc] init];
        _firstLabel.numberOfLines = 1;
        _firstLabel.textAlignment = NSTextAlignmentCenter;
        _firstLabel.backgroundColor = [UIColor redColor];
        _firstLabel.font = [UIFont systemFontOfSize:25];
        
        _secondLabel = [[UILabel alloc] init];
        _secondLabel.numberOfLines = 1;
        _secondLabel.textAlignment = NSTextAlignmentCenter;
        _secondLabel.backgroundColor = [UIColor greenColor];
        _secondLabel.font = [UIFont systemFontOfSize:25];
        
        [self.contentView addSubview:_firstLabel];
        [self.contentView addSubview:_secondLabel];
        
        self.backgroundColor = [UIColor blackColor];
    }
    
    return self;
}

@end

label简单的alloc init之后加到contentView中即可，不用向我这样设置这些属性，毕竟这种方式下C需要知道V的任何细节，所以这些属性应该由C来完成。

接下来在UICollectionViewDelegateFlowLayout协议中

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath;

的这个方法内，计算并返回当前M数据中所需的V的size (V就是一个容器，M是内容，所以知道内容之后就应该知道容器的大小)。

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    
    LCHModel *model = self.models[indexPath.row];
    
    CGSize sizeForFirstLabel = [model.firstString boundingRectWithSize:CGSizeMake([[UIScreen mainScreen] bounds].size.width, __FLT_MAX__) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,NSFontAttributeName:[UIFont systemFontOfSize:25]} context:nil].size;
    
    CGSize sizeForSecondLabel = [model.secondString boundingRectWithSize:CGSizeMake([[UIScreen mainScreen] bounds].size.width, __FLT_MAX__) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,NSFontAttributeName:[UIFont systemFontOfSize:25]} context:nil].size;

    return CGSizeMake(sizeForFirstLabel.width + sizeForSecondLabel.width, MAX(sizeForFirstLabel.height, sizeForSecondLabel.height));
    
}

然后在UICollectionViewDataSource的

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath;

这个方法中，详细设置V的subviews的frame

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    
    LCHCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"reuse" forIndexPath:indexPath];
    LCHModel *model = self.models[indexPath.row];
    cell.firstLabel.text = model.firstString;
    cell.secondLabel.text = model.secondString;
    
    CGSize sizeForFirstLabel = [model.firstString boundingRectWithSize:CGSizeMake([[UIScreen mainScreen] bounds].size.width, __FLT_MAX__) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,NSFontAttributeName:[UIFont systemFontOfSize:25]} context:nil].size;
    
    CGSize sizeForSecondLabel = [model.secondString boundingRectWithSize:CGSizeMake([[UIScreen mainScreen] bounds].size.width, __FLT_MAX__) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,NSFontAttributeName:[UIFont systemFontOfSize:25]} context:nil].size;
    
    CGRect firstLabelFrame = cell.firstLabel.frame;
    CGRect secondLabelFrame = cell.secondLabel.frame;
    firstLabelFrame.size = sizeForFirstLabel;
    secondLabelFrame.size = sizeForSecondLabel;
    secondLabelFrame.origin.x = sizeForFirstLabel.width;
    cell.firstLabel.frame = firstLabelFrame;
    cell.secondLabel.frame = secondLabelFrame;
    
    return cell;
}

这个Demo的地址如下：