ios - 尝试设置 NSLayoutConstraint 时出错

Question

尝试设置布局约束的宽度和高度时出现以下错误:

“由于未捕获的异常'NSInternalInconsistencyException'而终止应用程序，原因:'NSDictionaryOfVariableBindings失败，因为其中一个值为零，或者调用宏的方式有问题。无法为键“infoButton”分配值nil .键:( 信息按钮“

    [holderView addSubview:infoButton];
    // width constraint
    [holderView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[infoButton(==44)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(infoButton)]];

    // height constraint
    [holderView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[infoButton(==44)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(infoButton)]];

更新:

仍然没有工作，当我断点时仍然为零？

 [holderView addSubview:infoButton];
    holderView.userInteractionEnabled = YES;
    id views = @{@"infoButton": infoButton};

    [holderView addSubview:infoButton];
    // width constraint
    [holderView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[infoButton(==44)]" options:0 metrics:nil views:views]];

    // height constraint
    [holderView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[infoButton(==44)]" options:0 metrics:nil views:views]];

Answer 1

当您设置约束时，您的 infoButton 实例为 nil。