我正在尝试调试了解自动布局约束,我注意到在使用
xcode调试视图时(使用酷层事物)我注意到在视图中的一个元素上,约束看起来像这样
而观点确实忽略了这些限制.
所有约束具有相同的优先级(1000),因为我想要它们.所有约束都是使用接口构建器而不是通过代码进行的,并且IB中没有警告或冲突.
但在运行时我确实看到了这一点
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:0x79684f10 V:[UIImageView:0x79686800(>=160)]>","<NSLayoutConstraint:0x7968a310 V:[UIImageView:0x79686800]-(130.5)-| (Names: '|':UIView:0x79686790 )>","<NSLayoutConstraint:0x7968a340 V:|-(0)-[UIImageView:0x79686800] (Names: '|':UIView:0x79686790 )>","<NSLayoutConstraint:0x796997b0 'UIView-Encapsulated-Layout-Height' V:[CoverCell:0x79686570(192)]>","<NSAutoresizingMaskLayoutConstraint:0x7969cd30 h=-&- v=-&- UIView:0x79686790.height == CoverCell:0x79686570.height>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x79684f10 V:[UIImageView:0x79686800(>=160)]>
所以我从中了解到一些规则存在冲突,但我不确定如何阅读
> = 160是UIImageView上的规则,所以它的高度至少为160,而130.5是imageview的底部填充(所以当使用systemLayoutSizeFittingSize：UILayoutFittingCompressedSize时,高度不会是0.所以整个最小高度细胞是160 130.5)
剩下的错误我不明白.
约束有什么问题,为什么约束冲突发生在运行时而不是IB？
解决方法
XCode 6现在支持不同的布局.紧凑宽度|中存在这种灰色约束例如,任何高度布局,但您当前正在编辑任何宽度|任何高度.