iOS学习-2

1. 纯代码构建hello world

新建项目，删除scene相关，删除ViewController，删掉Main Interface，添加RootViewController。
修改AppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.rootViewController = [[RootViewController alloc]init];
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}

RootViewController.m创建UILable并添加

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    CGRect screen = [[UIScreen mainScreen]bounds];
    CGFloat labelWidth = 90;
    CGFloat labelHeight = 20;
    CGRect frame = CGRectMake((screen.size.width - labelWidth) / 2, 150, labelWidth, labelHeight);
    UILabel *label = [[UILabel alloc]initWithFrame:frame];
    label.text = @"Hello World";
    label.textColor = [UIColor blackColor];
    label.textAlignment = NSTextAlignmentCenter;
    [self.view addSubview:label];
}

运行查看结果：

image.png

2. UIView相关

创建一个界面，包含一个文本和一个按钮，点击按钮改变文本内容。
xlb实现：
创建项目：

image.png

(1) Deployment Info target 删除iPad
(2) Deployment Info Main Interface 清空
(3) 删除SceneDelegate.h和SceneDelegate.m
(4) 删除AppDelegate.m中的Scene相关代码。只保留didFinishLaunchingWithOptions方法。
(5) Info.plist 删除Application Scene Manifest 项
(6) AppDelegate.h添加

@property(strong, nonatomic) UIWindow *window;

(7) 创建界面，这里我们直接使用自动生成的ViewController，只创建一个xlb文件。
右键-new File，选择View，创建名为ViewController.xib，点击create完成创建。
打开xlb文件，点击左侧的File's Owner，在右侧的File's Owner Class中填入ViewController

image.png

然后点击左侧File's Owner图标，按住Ctrl键拖动到界面上

image.png
在弹出的Outlet选择view，完成。
(8)修改AppDelegate.m文件

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.rootViewController = [[ViewController alloc]initWithNibName:@"ViewController" bundle:nil];
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}

至此基础配置就完成来了，可以在xlb文件中写界面了。
拖动一个UILabel和一个UIButton到界面中，如图

image.png

(9) 按住ctrl拖动view到控制器，如图

image.png
设置view的name
同样拖动button到控制器，创建button的点击事件。

#import "ViewController.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UILabel *lebel;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}
- (IBAction)buttonClick:(id)sender {
    self.lebel.text = @"Hello World";
}


@end

运行可以实现效果。

(10)使用纯代码方式构建：
ViewController.m 代码

#import "ViewController.h"

@interface ViewController ()

@property(strong, nonatomic) UILabel *label;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    CGRect screen = [[UIScreen mainScreen]bounds];
    CGFloat labelWidth = 90;
    self.label = [[UILabel alloc]initWithFrame:CGRectMake((screen.size.width - labelWidth) / 2, 80, 90, 20)];
    self.label.text = @"Original";
    self.label.textAlignment = NSTextAlignmentCenter;
    [self.view addSubview:self.label];
    
    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
    button.frame = CGRectMake((screen.size.width - 90) / 2, 200, 90, 20);
    [button setTitle:@"button" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonClick) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}

-(void) buttonClick {
    self.label.text = @"Hello World";
}


@end