Question

我尝试使用autolayout和以下代码在容器视图中堆叠多个视图：

UIView* prevView = commentBox; // Set the prev view to the container
for(Comment* comment in [[post info] comments]){
    UIView* commentView = [[UIView alloc] initWithFrame:CGRectZero];
    [commentView setTranslatesAutoresizingMaskIntoConstraints:NO];
    [commentBox addSubview:commentView];

    // Vertically align with container view
    [commentBox addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[commentView]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(commentView)]];

    // Add a space of 8 between the previous view and the current view
    [commentBox addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[prevView]-8-[commentView(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(prevView, commentView)]];

    // Store the current view for the next round
    prevView = commentView;
}
// Finally, add a space between the last element and the container view
[commentBox addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[prevView]-8-[commentBox]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(prevView, commentBox)]];

commentBox本身在故事板中自动进行，这应该是安全的。

但是，当commentBox填充了子视图时，它会显示以下错误：

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:0x170097ca0 H:|-(0)-[UIView:0x170199e60]   (Names: '|':UIView:0x17019a8f0 )>",
    "<NSLayoutConstraint:0x170097cf0 H:[UIView:0x170199e60]-(0)-|   (Names: '|':UIView:0x17019a8f0 )>",
    "<NSLayoutConstraint:0x174099280 UIView:0x17419c8a0.width == UIView:0x17019a8f0.width>",
    "<NSLayoutConstraint:0x17409a180 'UIView-Encapsulated-Layout-Width' H:[UIView:0x17419c8a0(320)]>",
    "<NSLayoutConstraint:0x170098ec0 H:[UIView:0x170199e60]-(8)-[UIView:0x1701997e0]>",
    "<NSLayoutConstraint:0x170098f10 H:[UIView:0x1701997e0(100)]>",
    "<NSLayoutConstraint:0x170099050 H:[UIView:0x1701997e0]-(8)-[UIView:0x170199a50]>",
    "<NSLayoutConstraint:0x1700990a0 H:[UIView:0x170199a50(100)]>",
    "<NSLayoutConstraint:0x170099190 H:[UIView:0x170199a50]-(8)-[UIView:0x17019b110]>",
    "<NSLayoutConstraint:0x1700991e0 H:[UIView:0x17019b110(100)]>",
    "<NSLayoutConstraint:0x174099dc0 H:[UIView:0x17019b110]-(8)-[UIView:0x170199e60]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x174099dc0 H:[UIView:0x17019b110]-(8)-[UIView:0x170199e60]>

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.

我不知道如何解决这个问题。

我在iOS SDK 8.1中使用xCode 6.1

提前谢谢

Answer 1

我在代码中看到两个错误。首先，您不能在[prevView]中使用[prevView]来引用第一个水平约束，或者在最后一个约束中引用[commentBox]。您需要使用竖线字符“|”来引用它。其次，你不能在整个视图中制作硬限制（我的意思是大小和具有固定值的空格）（除非这些数字都完全加起来超级视图的宽度，即使那样你也不应该这样做它）。因此，您需要允许宽度或间距灵活，或者不要将最后一个约束放在commentView的右侧。

Autolayout：无法同时满足约束条件

1 个答案: