Question

我正在尝试以编程方式向UIWebView添加UIViewController，但我收到错误。我在下面粘贴了代码和错误（代码在viewDidLoad：

[self.view addSubview:self.webView];
NSDictionary *views = @{@"webView": self.webView};
NSArray *horizontal = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[webView]|"
                                                              options:0
                                                              metrics:nil
                                                                views:views];
NSArray *vertical = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[webView]|"
                                                            options:0
                                                            metrics:nil
                                                              views:views];
NSMutableArray *allConstraints = [NSMutableArray new];
[allConstraints addObjectsFromArray:horizontal];
[allConstraints addObjectsFromArray:vertical];
[self.view addConstraints:allConstraints];

- (UIWebView *)webView {
    if (!_webView) {
        _webView = [[UIWebView alloc] init];
        _webView.scalesPageToFit = YES;
        _webView.delegate = self;
    }
    return _webView;
}

我得到的错误是：

Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.     Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find  the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)

(
"<NSLayoutConstraint:0x14dbc5e0 V:|-(0)-[UIWebView:0x14da8010]   (Names: '|':UIView:0x14dae350 )>",
"<NSLayoutConstraint:0x14dbc640 V:[UIWebView:0x14da8010]-(0)-|   (Names: '|':UIView:0x14dae350 )>",
"<NSAutoresizingMaskLayoutConstraint:0x14dc2880 h=--& v=--& UIWebView:0x14da8010.midY == + 284>",
"<NSAutoresizingMaskLayoutConstraint:0x14e93e60 h=-&- v=-&- UIView:0x14dae350.height == _UIParallaxDimmingView:0x14dbcca0.height>",
"<NSAutoresizingMaskLayoutConstraint:0x14ec1130 h=--& v=--& V:[_UIParallaxDimmingView:0x14dbcca0(504)]>")

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x14dbc640 V:[UIWebView:0x14da8010]-(0)-|   (Names: '|':UIView:0x14dae350 )>

Break on objc_exception_throw to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

我正在尝试将UIWebView设置为设备的宽度，并从顶部的导航栏下方开始设置它的高度。这里还有什么我想念的吗？我为此阅读了以下内容：

http://www.thinkandbuild.it/learn-to-love-auto-layout-programmatically/

http://derpturkey.com/autosize-uitableviewcell-height-programmatically/

Answer 1

通常NSAutoresizingMaskLayoutConstraint的存在表示您需要为一个或多个视图将translatesAutoresizingMaskIntoConstraints设置为NO。试试这个：

[self.view addSubview:self.webView]; // you already have this line.
self.webview.translatesAutoresizingMaskIntoConstraints = NO; //add this line.

您也可以尝试使用webView的getter方法设置属性，而不是将其放在viewDidLoad中。

另外，您是否在覆盖[super viewDidLoad]？

时调用了viewDidLoad

UIWebView的Autolayout问题

1 个答案: