宏式懒加载
定义一个懒加载的宏
#define DYJ_LAZY(object, assignment) (object = object ?: assignment)
使用
//使用
- (UINavigationBar *)navBar
{
return DYJ_LAZY(_navBar, ({
UINavigationBar *bar = [[UINavigationBar alloc] init];
bar.barStyle = UINavigationBar.appearance.barStyle;
bar.translucent = YES;
[self.view addSubview:bar];
[bar setFrame:CGRectMake(0, 0, SCREEN_WIDTH, 64)];
bar;
}));
}
