使用 Objective-C 以编程方式创建 UIView，以在纵向和横向中工作

Question

我必须在 objective c 中创建一个视图，上面有两个标签，label1 有单行，label2 是基于内容的多行。

根据标签中的内容我想调整视图高度我该怎么做？

视图的宽度应为屏幕宽度的左右 20，使用以下代码我可以纵向显示，但横向显示不正确，它在右侧裁剪。我怎样才能显示正确的 20 横向？

纵向

横向

    UIView *emptyTreeView = [[UIView alloc] initWithFrame:CGRectMake(20,20,self.view.frame.size.width - 40,400)];
    UILabel *label1 =  [[UILabel alloc] initWithFrame:CGRectMake(30.0, 30.0, self.view.frame.size.width - 100, 30.0)];
    UILabel *label2 = [[UILabel alloc] initWithFrame:CGRectMake(30.0, 90.0, self.view.frame.size.width - 100, 100.0)];
    emptyTreeView.backgroundColor=[UIColor blueColor];
    label1.backgroundColor = [UIColor redColor];
    label1.textAlignment = NSTextAlignmentCenter;
    label1.textColor = [UIColor blackColor];
    label1.font = [UIFont boldSystemFontOfSize:18];
    label1.numberOfLines = 0;
    label1.text = @"The Page Cannot be displayed.";
    label2.backgroundColor = [UIColor whiteColor];
    label2.textAlignment = NSTextAlignmentCenter;
    label2.textColor = [UIColor grayColor];
    label2.font = [UIFont systemFontOfSize:15];
    label2.numberOfLines = 0;
    label2.text = @"Please use this feature or contact your internal contact person directly.";
    [emptyTreeView addSubview:label1];
    [emptyTreeView addSubview:label2];
    [self.view addSubview:emptyTreeView];

我做错了什么吗？

Answer 1

几点观察：

不要在 viewDidLayoutSubviews 中添加子视图。这仅用于调整 frame 值。
如果您引用 self.view，请引用它的 bounds，而不是它的 frame。前者用于 self.view 内的子视图坐标。后者在其父视图的坐标系中（现在可能不会引入任何差异，但只是错误的坐标系。

如果您希望视图在旋转时调整大小，请设置其 autoresizingMask，例如

emptyTreeView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleBottomMargin;

或

emptyTreeView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleBottomMargin;

现在，设置帧值和自动调整蒙版大小有点不合时宜了。我们通常会使用约束，例如

- (void)viewDidLoad {
    [super viewDidLoad];

    UIView *emptyTreeView = [[UIView alloc] init];
    UILabel *label1 =  [[UILabel alloc] init];
    UILabel *label2 = [[UILabel alloc] init];
    emptyTreeView.backgroundColor = [UIColor blueColor];
    label1.backgroundColor = [UIColor redColor];
    label1.textAlignment = NSTextAlignmentCenter;
    label1.textColor = [UIColor blackColor];
    label1.font = [UIFont boldSystemFontOfSize:18];
    label1.numberOfLines = 0;
    label1.text = @"The Page Cannot be displayed.";
    label2.backgroundColor = [UIColor whiteColor];
    label2.textAlignment = NSTextAlignmentCenter;
    label2.textColor = [UIColor grayColor];
    label2.font = [UIFont systemFontOfSize:15];
    label2.numberOfLines = 0;
    label2.text = @"Please use this feature or contact your internal contact person directly.";
    [emptyTreeView addSubview:label1];
    [emptyTreeView addSubview:label2];
    [self.view addSubview:emptyTreeView];

    emptyTreeView.translatesAutoresizingMaskIntoConstraints = false;
    label1.translatesAutoresizingMaskIntoConstraints = false;
    label2.translatesAutoresizingMaskIntoConstraints = false;

    [NSLayoutConstraint activateConstraints:@[
        [emptyTreeView.leftAnchor constraintEqualToAnchor:self.view.safeAreaLayoutGuide.leftAnchor constant:20],
        [emptyTreeView.rightAnchor constraintEqualToAnchor:self.view.safeAreaLayoutGuide.rightAnchor constant:-10],
        [emptyTreeView.topAnchor constraintEqualToAnchor:self.view.safeAreaLayoutGuide.topAnchor constant:20],

        [label1.leftAnchor constraintEqualToAnchor:emptyTreeView.leftAnchor constant:20],
        [label1.rightAnchor constraintEqualToAnchor:emptyTreeView.rightAnchor constant:-20],
        [label1.topAnchor constraintEqualToAnchor:emptyTreeView.topAnchor constant:20],

        [label2.leftAnchor constraintEqualToAnchor:emptyTreeView.leftAnchor constant:20],
        [label2.rightAnchor constraintEqualToAnchor:emptyTreeView.rightAnchor constant:-20],
        [label2.topAnchor constraintEqualToAnchor:label1.bottomAnchor constant:20],

        [emptyTreeView.bottomAnchor constraintEqualToAnchor:label2.bottomAnchor constant:20]
    ]];
}

请注意 translatesAutoresizingMaskIntoConstraints 是 false 和约束条件。

使用 Objective-C 以编程方式创建 UIView，以在纵向和横向中工作

Create UIView programmatically with Objective-C to work in both portrait and landscape

objective-c

uiview

ios