NSLayoutConstraint设置

Question

我正在尝试设置一个面板来显示一些信息。我很难让自动排版按我想要的那样工作。

这是我想要做的：

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我有一个headerView，一个UIImageView和5个标签。我想要标签垂直排列，我希望他们从UIImageView的8个间距。我可以很容易地垂直排列它们：

[contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[headerView]-[acresLabel]-[addedLabel(==acresLabel)]-[typeLabel(==acresLabel)]-[zonesLabel(==acresLabel)]-[sceneLabel(==acresLabel)]-|"
                                                                    options:0
                                                                    metrics:nil
                                                                      views:NSDictionaryOfVariableBindings(headerView, acresLabel, addedLabel, typeLabel, zonesLabel, sceneLabel)]];

但事实证明，让他们在图像视图中排成一行是乏味的/冗长的：

[contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[imageView]-[acresLabel]"
                                                                    options:0
                                                                    metrics:nil
                                                                      views:NSDictionaryOfVariableBindings(imageView, acresLabel)]];

[contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[imageView]-[addedLabel]"
                                                                    options:0
                                                                    metrics:nil
                                                                      views:NSDictionaryOfVariableBindings(imageView, addedLabel)]];

[contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[imageView]-[typeLabel]"
                                                                    options:0
                                                                    metrics:nil
                                                                      views:NSDictionaryOfVariableBindings(imageView, typeLabel)]];

[contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[imageView]-[zonesLabel]"
                                                                    options:0
                                                                    metrics:nil
                                                                      views:NSDictionaryOfVariableBindings(imageView, zonesLabel)]];

[contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[imageView]-[sceneLabel]"
                                                                    options:0
                                                                    metrics:nil
                                                                      views:NSDictionaryOfVariableBindings(imageView, sceneLabel)]];

这似乎是一种更好的方法，然后为图像视图的每个标签设置一个约束。我尝试将NSLayoutFormatAlignAllCenterX添加到第一个约束，但它将它们都设置为内容视图的中心X，不会使标签的中心X彼此对齐。垂直使用时，NSLayoutFormatAlignAllBaseline会出现错误和崩溃。

我将不得不再次对数据执行此操作(Acres：'value')。

Answer 1

有了NSLayoutFormatAlignAllCenterX，您就走上了正确的道路。

// NSDictionary* views ;
[NSLayoutConstraint constraintsWithVisualFormat:@"V:[headerView]-[acresLabel]"  options:0  metrics:nil  views:views] ;
// Use any of the horizontal NSLayoutFormats (NSLayoutFormatAlignAllLeft, NSLayoutFormatAlignAllRight, NSLayoutFormatAlignAllLeading, NSLayoutFormatAlignAllTrailing, NSLayoutFormatAlignAllCenterX)
[NSLayoutConstraint constraintsWithVisualFormat:@"V:[acresLabel]-[addedLabel(==acresLabel)]-[typeLabel(==acresLabel)]-[zonesLabel(==acresLabel)]-[sceneLabel(==acresLabel)]-|" options:NSLayoutFormatAlignAllCenterX  metrics:0  views:views] ;
[NSLayoutConstraint constraintsWithVisualFormat:@"H:[imageView]-[acresLabel]"  options:0  metrics:nil  views:views] ;