懒加载

顾名思义：用到时再去加载，而且也只加载一次

#import "XMGShopView.h"
#import "XMGShop.h"

@interface XMGShopView()
/** 图片控件 */
@property (nonatomic, strong) UIImageView *iconView;
/** 名字控件 */
@property (nonatomic, strong) UILabel *nameLabel;

@end

@implementation XMGShopView

+ (instancetype)shopView
{
    return [[self alloc] init];
}
# 懒加载模式 #
- (UIImageView *)iconView
{
    if (_iconView == nil) {
        UIImageView *iconView = [[UIImageView alloc] init];
        iconView.backgroundColor = [UIColor blueColor];
        [self addSubview:iconView];
        _iconView = iconView;
    }
    return _iconView;
}

- (UILabel *)nameLabel
{
    if (_nameLabel == nil) {
        UILabel *nameLabel = [[UILabel alloc] init];
        nameLabel.font = [UIFont systemFontOfSize:11];
        nameLabel.textAlignment = NSTextAlignmentCenter;
        nameLabel.backgroundColor = [UIColor redColor];
        [self addSubview:nameLabel];
        _nameLabel = nameLabel;
    }
    return _nameLabel;
}
/**
 * 这个方法专门用来布局子控件，一般在这里设置子控件的frame
 * 当控件本身的尺寸发生改变的时候，系统会自动调用这个方法
 * 
 */
- (void)layoutSubviews{
    // 一定要调用super的layoutSubviews
    [super layoutSubviews];
    
    CGFloat shopW = self.frame.size.width;
    CGFloat shopH = self.frame.size.height;
    self.iconView.frame = CGRectMake(0, 0, shopW, shopW);
    self.nameLabel.frame = CGRectMake(0, shopW, shopW, shopH - shopW);
}

- (void)setShop:(XMGShop *)shop
{
    _shop = shop;
    
    self.nameLabel.text = shop.name;
    self.iconView.image = [UIImage imageNamed:shop.icon];
}
@end