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我已经阅读了 Apple 关于自动布局的官方文档，并且UIScrollView：

RN-iOSSDK-6_0

我正在尝试“纯自动布局方法”。

我正在添加一个UILabel和一个UITextField。我希望两者都扩展到界面的宽度：

RootViewController.h

@interface rootViewController : UIViewController

@property (nonatomic, strong) UIScrollView *scrollView;
@property (nonatomic, strong) UIView *contentView;
@property (nonatomic, strong) UILabel *bigLetters;
@property (nonatomic, strong) UITextField *aTextField;


@end

viewDidLoad

- (void)viewDidLoad {
[super viewDidLoad];
[self.view setTranslatesAutoresizingMaskIntoConstraints:NO];
self.view.backgroundColor = [UIColor lightGrayColor];
_scrollView = [[UIScrollView alloc] init];
[_scrollView setTranslatesAutoresizingMaskIntoConstraints:NO];
_contentView = [[UIView alloc] init];
[_contentView setTranslatesAutoresizingMaskIntoConstraints:NO];
_bigLetters = [[UILabel alloc] init];
[_bigLetters setTranslatesAutoresizingMaskIntoConstraints:NO];
_bigLetters.font = [UIFont systemFontOfSize:30];
_bigLetters.textColor = [UIColor blackColor];
_bigLetters.backgroundColor = [UIColor clearColor];
_bigLetters.text = @"Why so small?";
_bigLetters.textAlignment = NSTextAlignmentCenter;
_aTextField = [[UITextField alloc] init];
_aTextField.backgroundColor = [UIColor whiteColor];
_aTextField.placeholder = @"A Text Box";
[_aTextField setTranslatesAutoresizingMaskIntoConstraints:NO];


[self.view addSubview:_scrollView];
[self.scrollView addSubview:_contentView];

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_scrollView]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_scrollView)]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_scrollView]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_scrollView)]];
[self.scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_contentView]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_contentView)]];
[self.scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_contentView]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_contentView)]];

[self.contentView addSubview:_bigLetters];
[self.contentView addSubview:_aTextField];

[self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[_bigLetters]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_bigLetters)]];
[self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[_aTextField]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_aTextField)]];
[self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[_bigLetters]-[_aTextField]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_bigLetters, _aTextField)]];
// Do any additional setup after loading the view.
}

我将两个元素都压在左上角，如下所示：

在此处输入图像描述

如果我将 _scrollView 切换到 a UIView，一切看起来都很好。我究竟做错了什么？

谢谢！

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1 回答 1

0

UIScrollViews 有点复杂。首先：

[self.view setTranslatesAutoresizingMaskIntoConstraints:NO];

你不应该那样做。您的根视图不需要使用自动布局。您的子视图需要它。

此外，滚动视图的 contentSize 由您放入其中的内容定义。如果您想要一个滚动视图屏幕大小的修复它的子视图之一到屏幕宽度（或八个）。你在那里看到的是你的滚动视图包裹了它的内容，宽度可能是标签的内在内容大小。

这就是它与视图一起使用的原因。希望能帮助到你！！

于 2016-04-25T03:27:59.230 回答