iOS Autolayout 让标签位于图像之上

Question

我正在尝试实现一个 UIPageController，以便我的用户可以在画廊上左右滑动。 UIImageView 将占据整个背景，而标签将像堆叠一样位于顶部。这是我在界面构建器中的尝试:

UIImageView 的大小检查器，因为下面有评论:

但是我在界面生成器中遇到了很多这样的错误:

2015-09-18 22:19:33.964 ParksonUI[10525:453297] 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:0x7aec77f0 V:[_UILayoutGuide:0x7aec7330]-(449)-[UILabel:0x7aec6ca0'Over 200 Tips and Tricks']>",
    "<NSLayoutConstraint:0x7aec78b0 V:[UILabel:0x7aec6ca0'Over 200 Tips and Tricks']-(20)-[_UILayoutGuide:0x7aec7440]>",
    "<_UILayoutSupportConstraint:0x7aec5ee0 V:[_UILayoutGuide:0x7aec7330(64)]>",
    "<_UILayoutSupportConstraint:0x7aec6690 V:|-(0)-[_UILayoutGuide:0x7aec7330]   (Names: '|':UIView:0x7aec7270 )>",
    "<_UILayoutSupportConstraint:0x7aec6540 V:[_UILayoutGuide:0x7aec7440(0)]>",
    "<_UILayoutSupportConstraint:0x7aec7220 _UILayoutGuide:0x7aec7440.bottom == UIView:0x7aec7270.bottom>",
    "<NSLayoutConstraint:0x7afea660 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7aec7270(519)]>"
)

我认为标签可能被推到了图像下方？

Answer 1

首先，一定要像一些大佬说的那样，在document outline的label前面加上imageView。之后，将 imageView 调整到主视图的所有边框并尝试以下约束:

• 底部空间到:Superview
• 将尾部对齐到:Superview
• 将前导对齐到:Superview
• 将顶部对齐到:Superview

还有这些标签:

• 底部空间到底部布局:所需距离
• 将引导线与 Superview 对齐:所需距离
• 宽度:所需宽度
• 高度:理想高度

希望它有用。