开头

• 这是分篇章，整篇请看零基础iOS开发学习日记

自定义根控制器

• xcode生成的项目默认是加载storyboard的，而我现在一般喜欢纯代码开发，所以要进行项目的初始设置

1. 删掉SceneDelegate.h/.m
2. AppDelegate.h 中添加@property (nonatomic, strong) UIWindow *window;
3. Info.plist删掉有Scene设置，删掉有Main的值
4. 删掉Main.storyboard
5. AppDelegate.m实现下面这个函数，可以理解为App的入口，app的一些初始化设置，都可以写在这个函数里

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
    //设置根控制器
    ViewController *vc = [ViewController new];
    self.window.rootViewController = vc;
    [self.window makeKeyAndVisible];
    return YES;
}
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UINavigationController

实际用处

• 管理有关联的页面

基础用法

• UINavigationController实际上就是个盒子，设置了根控制器后，从这个根控制器跳转的都会从里到外，放在这个盒子里。
• 设置app的根控制器，并将ViewController放入NavigationController中

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window  = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
    ViewController *vc = [ViewController new];
    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:vc];
    self.window.rootViewController = nav;
    [self.window makeKeyAndVisible];
    return YES;
}
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• ViewController跳转到testViewController，testViewController也放在这个盒子里

- (void)btnClick {
    testViewController *vc = [testViewController new];
    [self.navigationController pushViewController:vc animated:YES];
}
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• 界面弹出

//弹回上一个界面，如果是第一页无效
[self.navigationController popViewControllerAnimated:YES];
//弹到指定的界面，这个界面必须要在这个盒子中，而不能新建
ViewController *vc = self.navigationController.viewControllers[0];
[self.navigationController popToViewController:vc animated:YES];
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UINavigationBar

• UINavigationBar是添加UINavigationController后，状态栏显示的导航栏
• 主要由三部分组成，leftBarButton、rightBarButton、title。在实际开发中最常用的地方，也是设置左上角与右上角的按钮，和中间的标题

基本按钮添加

//标题
self.navigationItem.title = @"首页";
//系统样式按钮
UIBarButtonItem *right = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCamera target:self action:@selector(cameraClick)];
UIBarButtonItem *left = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemPlay target:self action:@selector(playClick)];
self.navigationItem.rightBarButtonItem = right;
self.navigationItem.leftBarButtonItem = left;
//自定义文字按钮
UIBarButtonItem *helpItem = [[UIBarButtonItem alloc]initWithTitle:@"常见问题" style:UIBarButtonItemStylePlain target:self action:@selector(helpItemClick)];
self.navigationItem.rightBarButtonItem = helpItem;
//自定义图片按钮
UIBarButtonItem *item = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"NavBack"] style:UIBarButtonItemStylePlain target:self action:@selector(backClick)];
self.navigationItem.leftBarButtonItem = item;
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• 以上，有几点要注意

1. 如果左右同时添加一个UIBarButtonItem，则只显示右边
2. 用self.navigationItem.rightBarButtonItem = helpItem这类方式添加，只会显示最左或者最右的按钮

添加多个按钮

• 添加多个按钮，会自动布局，并将标题挤过去

UIBarButtonItem *helpItem = [[UIBarButtonItem alloc]initWithTitle:@"常见问题" style:UIBarButtonItemStylePlain target:self action:@selector(helpItemClick)];
UIBarButtonItem *left1 = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(addClick)];
UIBarButtonItem *left2 = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemPlay target:self action:@selector(playClick)];
UIBarButtonItem *left3 = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemTrash target:self action:@selector(trashClick)];
self.navigationItem.leftBarButtonItems = @[left1, left2, left3, helpItem];
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自定义Button添加

• 自定义控件作为UIBarButtonItem，这里针对的情况是，按钮图片大小很大，而且需要另外修改约束，特别注意UIImage的渲染模式的设置

UIImage *image = [UIImage imageNamed:@"dv_icon1"];
//原图渲染
image = [image imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
[btn setImage:image forState:UIControlStateNormal];
//修改约束
CGFloat width = 44 * image.size.width / image.size.height;
[btn.widthAnchor constraintEqualToConstant:width].active = YES;
[btn.heightAnchor constraintEqualToConstant:44].active = YES;

[btn addTarget:self action:@selector(cameraClick) forControlEvents:UIControlEventTouchUpInside];
UIBarButtonItem *item = [[UIBarButtonItem alloc] initWithCustomView:btn];
self.navigationItem.leftBarButtonItem = item;
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修改外观

• UINavigationBar默认的渲染颜色是蓝色
• AppDelegate中设置

//渲染颜色
[[UINavigationBar appearance] setTintColor:[UIColor yellowColor]];
//标题样式
[[UINavigationBar appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName:[UIColor greenColor], NSFontAttributeName : [UIFont systemFontOfSize:30]}];
//标题背景
[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"NavBar64"] forBarMetrics:UIBarMetricsDefault];
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• 自定义UINavigationController 设置

//设置导航栏背景
[self.navigationBar setBackgroundImage:[UIImage imageNamed:@"NavBar64"] forBarMetrics:UIBarMetricsDefault];
//设置标题字体
[self.navigationBar setTitleTextAttributes:@{NSForegroundColorAttributeName:[UIColor greenColor], NSFontAttributeName : [UIFont systemFontOfSize:30]}];
//设置渲染的颜色
[self.navigationBar setTintColor:[UIColor blackColor]];
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内部跳转

• 内部跳转指的是，经过UINavigationController跳转后的界面，都会被保存在viewControllers的数组中
• 其中销毁过程，也是按照上面所讲从下往上放的顺序，从上往下销毁，如果中间有某个界面被销毁后，这个界面上的所有界面也会被销毁，销毁顺序为从下往上，例如，界面顺序从下往上依次为红绿蓝，一旦从蓝直接跳到红，会先销毁绿，在销毁蓝

//拿到导航控制器栈中的所有控制器
NSArray *vcs = self.navigationController.viewControllers;
UIViewController *vc = vcs[1];
[self.navigationController popToViewController:vc animated:YES];
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设置状态栏的样式

//颜色
- (UIStatusBarStyle)preferredStatusBarStyle {
    return UIStatusBarStyleLightContent;
}
//隐藏
- (BOOL)prefersStatusBarHidden {
    return YES;
}
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