如何使用自动布局以编程方式向滚动视图添加uiTextfield

debugcn 发表于 Dev

抢

我想使用自动布局以编程方式将文本字段添加到滚动视图，但是添加文本字段时，它以正确的大小显示在左上角，但没有宽度（也许2像素）。我如何才能将文本字段限制为屏幕的宽度？

以下是我的viewDidLoad方法：

    self.scrollView = [[UIScrollView alloc] init];
    [self.scrollView setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.view addSubview:self.scrollView];

    self.emailField = [[UITextField alloc] init];
    [self.emailField setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.scrollView addSubview:self.emailField];

    NSDictionary *views = @{ @"view":self.view, @"scrollView":self.scrollView,  @"textField":self.emailField};

    [self.view addConstraints: [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[scrollView]|"
    options:0
    metrics:nil
    views:views]];

    [self.view addConstraints: [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[scrollView]|"
    options:0
    metrics:nil
    views:views]];

    [self.scrollView addConstraints: [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[textField]|"
    options:0
    metrics:nil
    views:views]];

    [self.scrollView addConstraints: [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[textField(46)]"
    options:0
    metrics:nil
    views:views]];

桑迪普

我使用了与您发布的代码相同的代码，并修改了一些约束并添加了一些约束。

 UITextField *emailField = [[UITextField alloc] init];
    emailField.backgroundColor = [UIColor lightGrayColor];
    emailField.translatesAutoresizingMaskIntoConstraints = NO;
    self.emailField = emailField;

    UIScrollView *scrollView = [[UIScrollView alloc] init];

    self.scrollView = scrollView;
    [self.scrollView setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.view addSubview:self.scrollView];

    NSDictionary *views = @{ @"view":self.view, @"scrollView":self.scrollView,  @"textField":self.emailField, @"topLayoutGuide": self.topLayoutGuide};

    [self.view addConstraints: [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[scrollView]|"
                                                                       options:0
                                                                       metrics:nil
                                                                         views:views]];

    [self.view addConstraints: [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[scrollView]|"
                                                                       options:0
                                                                       metrics:nil
                                                                         views:views]];

    [self.emailField setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.scrollView addSubview:self.emailField];


    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.emailField
                                                          attribute:NSLayoutAttributeLeading
                                                          relatedBy:NSLayoutRelationEqual
                                                             toItem:self.scrollView
                                                          attribute:NSLayoutAttributeLeading
                                                         multiplier:1.0
                                                           constant:10]];
    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.emailField
                                                          attribute:NSLayoutAttributeTrailing
                                                          relatedBy:NSLayoutRelationEqual
                                                             toItem:self.scrollView
                                                          attribute:NSLayoutAttributeTrailing
                                                         multiplier:1.0
                                                           constant:10]];

    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.emailField attribute:NSLayoutAttributeWidth
                                                          relatedBy:NSLayoutRelationEqual
                                                             toItem:self.scrollView
                                                          attribute:NSLayoutAttributeWidth
                                                         multiplier:1.0
                                                           constant:-20]];

    [self.view addConstraints: [NSLayoutConstraint constraintsWithVisualFormat:@"V:[topLayoutGuide][textField(46)]"
                                                                             options:0
                                                                             metrics:nil
                                                                               views:views]];

重要的约束是宽度约束，它与scrollView的边界有关。如果您未通过自动布局在scrollView中定义子视图的宽度，则scrollView的contentSize会模棱两可，因此无法正确确定内容的宽度。“ |” scrollView的自动布局格式是contentSize边缘。

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