UINavigationController练习

布满荆棘的人生 2022-08-20 04:27 224阅读 0赞

#import "AppDelegate.h"
    #import <UIKit/UIKit.h>
    #import "RootViewController.h"
    @interface AppDelegate ()
    
    @end
    
    @implementation AppDelegate
    
    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
        
        float sysVersion=[[UIDevice currentDevice]systemVersion].floatValue;
        if (sysVersion>=8.0) {
            UIUserNotificationType type=UIUserNotificationTypeBadge | UIUserNotificationTypeAlert | UIUserNotificationTypeSound;
            UIUserNotificationSettings *setting=[UIUserNotificationSettings settingsForTypes:type categories:nil];
            [[UIApplication sharedApplication]registerUserNotificationSettings:setting];
        }
        
        UIWindow* w = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
        w.backgroundColor = [UIColor whiteColor];
        self.window = w;
        RootViewController* r =[[RootViewController alloc] init];
        UINavigationController* navBar = [[UINavigationController alloc] initWithRootViewController:r];
        w.rootViewController = navBar;
        [w makeKeyAndVisible];
        return YES;
    }

#import <UIKit/UIKit.h>
    
    @interface RootViewController : UIViewController
    
    @end

#import "RootViewController.h"
    #import "SecondViewController.h"
    
    @implementation RootViewController
    -(void)viewWillAppear:(BOOL)animated
    {
        self.navigationController.navigationBar.barStyle = UIBarStyleBlack;
        [self.navigationController setToolbarHidden:NO animated:YES];
    }
    -(void)viewDidLoad
    {
        [super viewDidLoad];
        
        UIButton* btn = [UIButton buttonWithType:UIButtonTypeCustom];
        [btn setFrame:CGRectMake(20, 64, 80, 40)];
        [btn setBackgroundColor:[UIColor brownColor]];
        [btn setTitle:@"添加" forState:UIControlStateNormal];
        [btn addTarget:self action:@selector(BtnClicked:) forControlEvents:UIControlEventTouchUpInside];
        [self.view addSubview:btn];   
        
        UIBarButtonItem* BarBtn = [[UIBarButtonItem alloc] initWithTitle:@"随机背景" style:UIBarButtonItemStylePlain target:self action:@selector(onClick:)];
        self.navigationItem.leftBarButtonItem = BarBtn;
        
        @try {
            UINavigationItem* item = self.navigationController.navigationBar.items[0];
            NSLog(@"%p",self.navigationItem);
            NSLog(@"%p",item);
            item.title = @"HelloWorld";
        }
        @catch (NSException *exception) {
            NSLog(@"%@",exception.description);
        }
        @finally {
            
        }
    }
    -(void)onClick:(UIBarButtonItem*) ABarBtn
    {
        CGFloat r = ( arc4random() % 256 / 256.0 );
        CGFloat g = ( arc4random() % 256 / 256.0 );
        CGFloat b = ( arc4random() % 256 / 256.0 );
        UIColor* c2 = [UIColor colorWithRed:r green:g blue:b alpha:1];
        
        self.view.backgroundColor = c2;
    }
    -(void)BtnClicked:(UIButton*)abtn
    {
        SecondViewController* sec = [[SecondViewController alloc] init];
        [self.navigationController pushViewController:sec animated:NO];
    }
    @end

#import <UIKit/UIKit.h>
    
    @interface SecondViewController : UIViewController
    
    @end

#import "SecondViewController.h"
    
    @implementation SecondViewController
    
    -(void)viewDidLoad
    {
        [super viewDidLoad];
        self.view.backgroundColor = [UIColor blueColor];
    }
    -(void)viewWillAppear:(BOOL)animated
    {
        UINavigationItem* item = self.navigationController.navigationBar.items[1];
        [self.navigationController setToolbarHidden:YES animated:YES];
        item.title = @"HelloWorldSec";
    }
    @end

个人对这个ui组件使用的理解

1，虽然UINavigationController继承于UIViewController,但是UIViewController保留了访问导航的属性，这样方便了各自实例的通讯。

2，自己写的类，如果要继承于UIViewController的话，最好直接继承，如果继承UITabViewController，虽然也有UINavigationController属性，但访问不到，为nil.

3，UINavigationController是栈管理的方式。

4，UINavigationController会为每一个实例创建个UINavigationItem.通过self.navigationItem与self.navigationController.navigationBar.item\[0\]的访问一样.

5，对navigationBar的设置都是全局的，不管在显示哪个ViewController.

6，这个navigationBar与Controller的View坐标重叠，如果新建subview，并且要显示出来，那么就得要考虑navigationBar的默认高度44.