iOS 重构之路 - 分类属性懒加载

iOS 分类属性实现懒加载
(用途:项目重构,继承->组合)

创建控制器分类 UIViewController+Helper.h

.h文件
#import <UIKit/UIKit.h>
#import "AnimationObject.h"

@interface UIViewController (Helper)

@property (strong, nonatomic) UITableView *tableView;

+(AnimationObject *)animation;;

@end

.m文件

#import "UIViewController+Helper.h"
#import <objc/runtime.h>

@interface UIViewController ()<UITableViewDataSource,UITableViewDelegate>

@end

@implementation UIViewController (Helper)

@dynamic tableView;

+(AnimationObject *)animation{
    AnimationObject * ani = objc_getAssociatedObject(self, _cmd);
    if (!ani) {
        ani = [[AnimationObject alloc]init];
        objc_setAssociatedObject(self, _cmd, ani, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    return ani;
}

- (UITableView *)tableView {
    UITableView* table = objc_getAssociatedObject(self, _cmd);
    if (table == nil) {
        table = [[UITableView alloc] initWithFrame:CGRectZero style:UITableViewStylePlain];
        [table registerClass:[UITableViewCell class] forCellReuseIdentifier:@"UITableViewCell"];
        table.layer.borderColor = [UIColor grayColor].CGColor;
        table.layer.borderWidth = 1;
        table.delegate = self;
        table.dataSource = self;
        objc_setAssociatedObject(self, _cmd, table, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    
    return table;
}

总结:tableView一类有代理方法的属性用非类方法;动画对象一类用类方法;