自定义cell
#pragma mark — 自定义cell
#import "SelfSizingCollectCell.h"
#import "Masonry.h"
#define itemHeight 60
@implementation SelfSizingCollectCell
- (instancetype)initWithFrame:(CGRect)frame{
self = [super initWithFrame:frame];
if (self) {
self.contentView.backgroundColor = [UIColor redColor];
// 用约束来初始化控件:
self.textLabel = [[UILabel alloc] init];
self.textLabel.textAlignment =NSTextAlignmentCenter;
self.textLabel.backgroundColor = [UIColor greenColor];
[self.contentView addSubview:self.textLabel];
#pragma mark — 如果使用CGRectMake来布局,是需要在preferredLayoutAttributesFittingAttributes方法中去修改textlabel的frame的
// self.textLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, 30)];
#pragma mark — 如果使用约束来布局,则无需在preferredLayoutAttributesFittingAttributes方法中去修改cell上的子控件l的frame
[self.textLabel mas_makeConstraints:^(MASConstraintMaker *make) {
// make 代表约束:
make.top.equalTo(self.contentView).with.offset(0);
make.left.equalTo(self.contentView).with.offset(0);
make.height.equalTo(@(itemHeight/2));
make.right.equalTo(self.contentView).with.offset(0);
}];
}
return self;
}
#pragma mark — 实现自适应文字宽度的关键步骤:item的layoutAttributes
- (UICollectionViewLayoutAttributes *)preferredLayoutAttributesFittingAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes{
UICollectionViewLayoutAttributes *attributes = [super preferredLayoutAttributesFittingAttributes:layoutAttributes];
CGRect rect = [self.textLabel.text boundingRectWithSize:CGSizeMake(CGFLOAT_MAX, itemHeight) options:NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesFontLeading | NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName: [UIFont systemFontOfSize:14]} context:nil];
rect.size.width +=8;
rect.size.height+=8;
attributes.frame = rect;
return attributes;
}
@end
Controller中关键
#pragma mark — 视图控制器中使用:(关键)
layout.estimatedItemSize = CGSizeMake(20, 60); // layout约束这边必须要用estimatedItemSize才能实现自适应,使用itemSzie无效
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