当在
WKWebView
中输入框获取焦点时,会出现一个约束错误。
代码:
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad();
let wv = WKWebView(frame: CGRect(x: 100, y: 100, width: 100, height: 100));
wv.loadHTMLString("<input type='text'/>", baseURL: nil); // it also can be select, it makes no difference
view.addSubview(wv);
}
}
错误日志:
2017-11-05 00:26:28.861439+0700 achievator[20048:75393577] [LayoutConstraints] 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) (
"<NSAutoresizingMaskLayoutConstraint:0x60c0000955e0 h=-&- v=-&- UIToolbar:0x7f8540419570.width ==
_UIInputViewContent:0x7f8540411830.width (active)>",
"<NSAutoresizingMaskLayoutConstraint:0x60c000095720 h=--& v=--& _UIInputViewContent:0x7f8540411830.width == 0 (active)>",
"<NSLayoutConstraint:0x60800009a9a0 H:|-(0)-[_UIButtonBarStackView:0x7f854041b2d0] (active, names: '|':_UIToolbarContentView:0x7f8540402de0 )>",
"<NSLayoutConstraint:0x60800009a9f0 _UIButtonBarStackView:0x7f854041b2d0.trailing == _UIToolbarContentView:0x7f8540402de0.trailing + 8 (active)>",
"<NSLayoutConstraint:0x608000099a00 _UIToolbarContentView:0x7f8540402de0.trailing == UIToolbar:0x7f8540419570.trailing (active)>",
"<NSLayoutConstraint:0x608000099aa0 H:|-(0)-[_UIToolbarContentView:0x7f8540402de0] (active, names: '|':UIToolbar:0x7f8540419570 )>",
"<NSLayoutConstraint:0x6040000981a0 H:|-(0)-[_UIModernBarButton:0x7f854050ef70] (active, names: '|':_UIButtonBarButton:0x7f854050e7f0 )>",
"<NSLayoutConstraint:0x6040000981f0 H:[_UIModernBarButton:0x7f854050ef70]-(>=8)-| (active, names: '|':_UIButtonBarButton:0x7f854050e7f0 )>",
"<NSLayoutConstraint:0x6040000999b0 H:|-(8)-[_UIModernBarButton:0x7f8540512450'Done'] (active, names: '|':_UIButtonBarButton:0x7f8540511660 )>",
"<NSLayoutConstraint:0x604000099a00 H:[_UIModernBarButton:0x7f8540512450'Done']-(0)-| (active, names: '|':_UIButtonBarButton:0x7f8540511660 )>",
"<NSLayoutConstraint:0x60c000094690 'UISV-canvas-connection' UILayoutGuide:0x6080001a9a00'UIViewLayoutMarginsGuide'.leading ==
_UIButtonBarButton:0x7f854050e7f0.leading (active)>",
"<NSLayoutConstraint:0x60c0000946e0 'UISV-canvas-connection' UILayoutGuide:0x6080001a9a00'UIViewLayoutMarginsGuide'.trailing ==
_UIButtonBarButton:0x7f8540511660.trailing (active)>",
"<NSLayoutConstraint:0x60c000094780 'UISV-spacing' H:[_UIButtonBarButton:0x7f854050e7f0]-(0)-[UIView:0x7f854050f4c0] (active)>",
"<NSLayoutConstraint:0x60c000094960 'UISV-spacing' H:[UIView:0x7f854050f4c0]-(0)-[_UIButtonBarButton:0x7f854050ea30] (active)>",
"<NSLayoutConstraint:0x60c000094a00 'UISV-spacing' H:[_UIButtonBarButton:0x7f854050ea30]-(0)-[UIView:0x7f8540511480] (active)>",
"<NSLayoutConstraint:0x60c000094a50 'UISV-spacing' H:[UIView:0x7f8540511480]-(0)-[_UIButtonBarButton:0x7f8540511660] (active)>",
"<NSLayoutConstraint:0x60800009a6d0 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x6080001a9a00'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':_UIButtonBarStackView:0x7f854041b2d0 )>",
"<NSLayoutConstraint:0x60800009a770 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x6080001a9a00'UIViewLayoutMarginsGuide']-(0)-|(LTR) (active, names: '|':_UIButtonBarStackView:0x7f854041b2d0 )>" )
Will attempt to recover by breaking constraint <NSLayoutConstraint:0x6040000981f0 H:[_UIModernBarButton:0x7f854050ef70]-(>=8)-| (active, names: '|':_UIButtonBarButton:0x7f854050e7f0 )>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful. 2017-11-05 00:26:28.863156+0700 achievator[20048:75393577] [LayoutConstraints] 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) (
"<NSAutoresizingMaskLayoutConstraint:0x60c0000955e0 h=-&- v=-&- UIToolbar:0x7f8540419570.width ==
_UIInputViewContent:0x7f8540411830.width (active)>",
"<NSAutoresizingMaskLayoutConstraint:0x60c000095720 h=--& v=--& _UIInputViewContent:0x7f8540411830.width == 0 (active)>",
"<NSLayoutConstraint:0x60800009a9a0 H:|-(0)-[_UIButtonBarStackView:0x7f854041b2d0] (active, names: '|':_UIToolbarContentView:0x7f8540402de0 )>",
"<NSLayoutConstraint:0x60800009a9f0 _UIButtonBarStackView:0x7f854041b2d0.trailing == _UIToolbarContentView:0x7f8540402de0.trailing + 8 (active)>",
"<NSLayoutConstraint:0x608000099a00 _UIToolbarContentView:0x7f8540402de0.trailing == UIToolbar:0x7f8540419570.trailing (active)>",
"<NSLayoutConstraint:0x608000099aa0 H:|-(0)-[_UIToolbarContentView:0x7f8540402de0] (active, names: '|':UIToolbar:0x7f8540419570 )>",
"<NSLayoutConstraint:0x604000098560 H:|-(>=5)-[_UIModernBarButton:0x7f8540510b40] (active, names: '|':_UIButtonBarButton:0x7f854050ea30 )>",
"<NSLayoutConstraint:0x604000098650 H:[_UIModernBarButton:0x7f8540510b40]-(>=5)-| (active, names: '|':_UIButtonBarButton:0x7f854050ea30 )>",
"<NSLayoutConstraint:0x6040000999b0 H:|-(8)-[_UIModernBarButton:0x7f8540512450'Done'] (active, names: '|':_UIButtonBarButton:0x7f8540511660 )>",
"<NSLayoutConstraint:0x604000099a00 H:[_UIModernBarButton:0x7f8540512450'Done']-(0)-| (active, names: '|':_UIButtonBarButton:0x7f8540511660 )>",
"<NSLayoutConstraint:0x60c000094690 'UISV-canvas-connection' UILayoutGuide:0x6080001a9a00'UIViewLayoutMarginsGuide'.leading ==
_UIButtonBarButton:0x7f854050e7f0.leading (active)>",
"<NSLayoutConstraint:0x60c0000946e0 'UISV-canvas-connection' UILayoutGuide:0x6080001a9a00'UIViewLayoutMarginsGuide'.trailing ==
_UIButtonBarButton:0x7f8540511660.trailing (active)>",
"<NSLayoutConstraint:0x60c000094780 'UISV-spacing' H:[_UIButtonBarButton:0x7f854050e7f0]-(0)-[UIView:0x7f854050f4c0] (active)>",
"<NSLayoutConstraint:0x60c000094960 'UISV-spacing' H:[UIView:0x7f854050f4c0]-(0)-[_UIButtonBarButton:0x7f854050ea30] (active)>",
"<NSLayoutConstraint:0x60c000094a00 'UISV-spacing' H:[_UIButtonBarButton:0x7f854050ea30]-(0)-[UIView:0x7f8540511480] (active)>",
"<NSLayoutConstraint:0x60c000094a50 'UISV-spacing' H:[UIView:0x7f8540511480]-(0)-[_UIButtonBarButton:0x7f8540511660] (active)>",
"<NSLayoutConstraint:0x60800009a6d0 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x6080001a9a00'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':_UIButtonBarStackView:0x7f854041b2d0 )>",
"<NSLayoutConstraint:0x60800009a770 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x6080001a9a00'UIViewLayoutMarginsGuide']-(0)-|(LTR) (active, names: '|':_UIButtonBarStackView:0x7f854041b2d0 )>" )
Will attempt to recover by breaking constraint <NSLayoutConstraint:0x604000098650 H:[_UIModernBarButton:0x7f8540510b40]-(>=5)-| (active, names: '|':_UIButtonBarButton:0x7f854050ea30 )>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillHideNotification, object: nil, queue: nil) { (notification) in self.webView.scrollView.contentOffset.y = 0 }
@swalkner 如果偏移量不为0,则可以在keyboardWillShowNotification
中获取内容偏移值,并在keyboardWillHideNotification
中相应地设置它。 - mc_plectrum