Objective C：如何以编程方式在安全区域内创建 self.view

使用Objective C编程语言，我们可以以编程方式在安全区域内创建self.view。安全区域是指屏幕上不受刘海、圆角或其他设备边缘影响的区域。在创建视图时，我们应该确保视图的内容不会被裁剪或被遮挡。

objective-c
#import 
@interface ViewController : UIViewController
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    
    // 创建一个新的视图
    UIView *myView = [[UIView alloc] init];
    myView.backgroundColor = [UIColor redColor];
    
    // 将视图添加到安全区域内
    [self.view addSubview:myView];
    
    // 使用自动布局将视图与安全区域边缘对齐
    UILayoutGuide *guide = self.view.safeAreaLayoutGuide;
    [myView.leadingAnchor constraintEqualToAnchor:guide.leadingAnchor].active = YES;
    [myView.trailingAnchor constraintEqualToAnchor:guide.trailingAnchor].active = YES;
    [myView.topAnchor constraintEqualToAnchor:guide.topAnchor].active = YES;
    [myView.bottomAnchor constraintEqualToAnchor:guide.bottomAnchor].active = YES;
}
@end

objective-c
#import 
@interface ViewController : UIViewController
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    
    // 创建一个包含标签和按钮的容器视图
    UIView *containerView = [[UIView alloc] init];
    containerView.backgroundColor = [UIColor whiteColor];
    
    // 将容器视图添加到安全区域内
    [self.view addSubview:containerView];
    
    // 使用自动布局将容器视图与安全区域边缘对齐
    UILayoutGuide *guide = self.view.safeAreaLayoutGuide;
    [containerView.leadingAnchor constraintEqualToAnchor:guide.leadingAnchor].active = YES;
    [containerView.trailingAnchor constraintEqualToAnchor:guide.trailingAnchor].active = YES;
    [containerView.topAnchor constraintEqualToAnchor:guide.topAnchor].active = YES;
    [containerView.bottomAnchor constraintEqualToAnchor:guide.bottomAnchor].active = YES;
    
    // 创建一个标签
    UILabel *label = [[UILabel alloc] init];
    label.text = @"Hello, World!";
    label.textAlignment = NSTextAlignmentCenter;
    
    // 将标签添加到容器视图
    [containerView addSubview:label];
    
    // 使用自动布局将标签居中显示
    [label.centerXAnchor constraintEqualToAnchor:containerView.centerXAnchor].active = YES;
    [label.centerYAnchor constraintEqualToAnchor:containerView.centerYAnchor].active = YES;
    
    // 创建一个按钮
    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
    [button setTitle:@"Click Me" forState:UIControlStateNormal];
    
    // 将按钮添加到容器视图
    [containerView addSubview:button];
    
    // 使用自动布局将按钮放置在标签下方
    [button.centerXAnchor constraintEqualToAnchor:containerView.centerXAnchor].active = YES;
    [button.topAnchor constraintEqualToAnchor:label.bottomAnchor constant:20].active = YES;
}
@end