标签：controls original eal pch appear lap pvc 建议 构造方法
当你创建一个继承与UITabBarController的子类 并想给其自定义构造方法 传一些值的时候这时候问题出现了：
在创建的时候里面的init方法回调用了 viewdidload，导致每次传值的时候都会在viewdidload加载完了之后传的值才能传过去
如下代码
- (instancetype)initWithURLStrings:(NSArray *)urls{ self = [super init];//在调用init的时候回调用viewDidLoad 导致参数传入进来时已经加载完了 if (self) {
self.urls = urls; } return self; } - (void)viewDidLoad { [super viewDidLoad]; [self setUpChild]; self.tabBar.backgroundColor = [UIColor whiteColor]; } - (void)setUpChild{ // 1.初始化子控制器 KHHomeVC *home = [[KHHomeVC alloc] initWithURL:self.urls[0]]; [self addChildVc:home title:@"首页" image:@"tab_home_n" selectedImage:@"tab_home_s"]; KHVipVC *vipVC = [[KHVipVC alloc] initWithURL:self.urls[1]]; [self addChildVc:vipVC title:@"会员" image:@"tab_user_n" selectedImage:@"tab_user_s"]; KHMineDetailVC *settingVC = [[KHMineDetailVC alloc] initWithURL:self.urls[2]]; [self addChildVc:settingVC title:@"设置" image:@"tab_setting_n" selectedImage:@"tab_setting_s"]; } - (void)addChildVc:(UIViewController *)childVc title:(NSString *)title image:(NSString *)image selectedImage:(NSString *)selectedImage { // 设置子控制器的文字 childVc.title = title; // 同时设置tabbar和navigationBar的文字 // 设置子控制器的图片 childVc.tabBarItem.image = [UIImage imageNamed:image]; if (iOS7) { childVc.tabBarItem.selectedImage = [[UIImage imageNamed:selectedImage] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal]; } else { childVc.tabBarItem.selectedImage = [UIImage imageNamed:selectedImage]; } // 设置文字的样式 NSMutableDictionary *textAttrs = [NSMutableDictionary dictionary]; textAttrs[NSForegroundColorAttributeName] = [UIColor colorWithRed:136/255.0 green:136/255.0 blue:136/255.0 alpha:1]; NSMutableDictionary *selectTextAttrs = [NSMutableDictionary dictionary]; selectTextAttrs[NSForegroundColorAttributeName] = [UIColor colorWithRed:0 green:183/255.0 blue:283/255.0 alpha:1]; [childVc.tabBarItem setTitleTextAttributes:textAttrs forState:UIControlStateNormal]; [childVc.tabBarItem setTitleTextAttributes:selectTextAttrs forState:UIControlStateSelected]; // 先给外面传进来的小控制器 包装 一个导航控制器 KHNavigationController *nav = [[KHNavigationController alloc] initWithRootViewController:childVc]; nav.navigationBarHidden = YES; // 添加为子控制器 [self addChildViewController:nav]; }
这是怎么回事的 我们知道在一般控制器中我们想要自定义构造方法 会先走完初始化方法然后再走 viewDidLoad 但是这个UITabBarController怎么这么特殊呢呢？
经过一番查找终于知道了原来这是UITabBarController的一个特性
其实UITabBarController在init的时候，会增UITabbar到self.view，这时候必须加载self.view出来，从而就调用了loadview，进而调用viewdidload、viewwillappear等。这个是UITabBarController的特性
UITabBarController在调用【super init】的时候，系统调用了self.view的东西，但是此时view还没加载出来，于是系统强制先调用viewdidload去加载self.view，最后加载完了，再接着走init方法中的 if(self)条件语句。
解决方案：
就是不要在viewdidload 方法里写加载界面的代码，可以单独再写个方法，直接在init结束的时候调用。所以我的建议就是直接把viewdidload和viewwillappear方法删了，加载界面全都在init里写，如下：
- (instancetype)initWithURLStrings:(NSArray *)urls{ self = [super init];//在调用init的时候回调用viewDidLoad 导致参数传入进来时已经加载完了 if (self) { self.urls = urls; //初始化数据 [self setUpChild]; //这是解决的重点 } return self; } - (void)viewDidLoad { [super viewDidLoad]; self.tabBar.backgroundColor = [UIColor whiteColor]; } - (void)setUpChild{ // 1.初始化子控制器 KHHomeVC *home = [[KHHomeVC alloc] initWithURL:self.urls[0]]; [self addChildVc:home title:@"首页" image:@"tab_home_n" selectedImage:@"tab_home_s"]; KHVipVC *vipVC = [[KHVipVC alloc] initWithURL:self.urls[1]]; [self addChildVc:vipVC title:@"会员" image:@"tab_user_n" selectedImage:@"tab_user_s"]; KHMineDetailVC *settingVC = [[KHMineDetailVC alloc] initWithURL:self.urls[2]]; [self addChildVc:settingVC title:@"设置" image:@"tab_setting_n" selectedImage:@"tab_setting_s"]; } - (void)addChildVc:(UIViewController *)childVc title:(NSString *)title image:(NSString *)image selectedImage:(NSString *)selectedImage { // 设置子控制器的文字 childVc.title = title; // 同时设置tabbar和navigationBar的文字 // 设置子控制器的图片 childVc.tabBarItem.image = [UIImage imageNamed:image]; if (iOS7) { childVc.tabBarItem.selectedImage = [[UIImage imageNamed:selectedImage] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal]; } else { childVc.tabBarItem.selectedImage = [UIImage imageNamed:selectedImage]; } // 设置文字的样式 NSMutableDictionary *textAttrs = [NSMutableDictionary dictionary]; textAttrs[NSForegroundColorAttributeName] = [UIColor colorWithRed:136/255.0 green:136/255.0 blue:136/255.0 alpha:1]; NSMutableDictionary *selectTextAttrs = [NSMutableDictionary dictionary]; selectTextAttrs[NSForegroundColorAttributeName] = [UIColor colorWithRed:0 green:183/255.0 blue:283/255.0 alpha:1]; [childVc.tabBarItem setTitleTextAttributes:textAttrs forState:UIControlStateNormal]; [childVc.tabBarItem setTitleTextAttributes:selectTextAttrs forState:UIControlStateSelected]; // 先给外面传进来的小控制器 包装 一个导航控制器 KHNavigationController *nav = [[KHNavigationController alloc] initWithRootViewController:childVc]; nav.navigationBarHidden = YES; // 添加为子控制器 [self addChildViewController:nav]; }
我发现只有继承自UINavigationController和UITabBarController的类的init函数会产生loadView、viewDidLoad函数在初始化［super init］函数调用后就执行，一般UIViewController没有这个问题
@implementation UIViewControllerSubclass - (id)init { NSLog(@"0"); if (self = [super init]) { NSLog(@"1"); } return self; } - (void)loadView { [super loadView]; NSLog(@"2"); } - (void)viewDidLoad { [super viewDidLoad]; NSLog(@"3"); } @end
console output
0 2 3 1
d
标签：controls original eal pch appear lap pvc 建议 构造方法
原文地址：http://www.cnblogs.com/junhuawang/p/6285257.html
