如何正确设置此布局的约束

Question

我已经尝试了很长时间了，但由于约束问题不断崩溃…

如何设置这种布局，使其在iPhone 3g, 4和5以及iPad上工作?

_______TOP OF SCREEN________

Table View should attach to top of screen and with 5 pixels to the Label below
flexible in height so it works on iPhone 5 and 6

____________________________

Label with fixed distance to table View above and button below
____________________________
Button with fixed distance to Label above and fixed distance to bottom of screen
____________________________
      Bottom of screen

所以基本上所有的距离和高度都是固定的除了表格的高度它应该填充屏幕顶部和标签

之间的可用区域

每当我设置这样的限制，我总是在iOS 6.1的iPhone 3上崩溃:

 2013-03-16 23:12:51.013 BMWhat Test[64196:907] 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) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x1d1f2d70 h=-&- v=-&- UIView:0x1d1aac20.height == UITransitionView:0x1d174220.height - 20>",
    "<NSLayoutConstraint:0x1d1c03b0 V:[UILabel:0x1c58f100(21)]>",
    "<NSLayoutConstraint:0x1d1ce780 V:[UITableView:0x1cbd9000(469)]>",
    "<NSLayoutConstraint:0x1c5aff30 V:[UIButton:0x1d1d1bb0(44)]>",
    "<NSLayoutConstraint:0x1d1c0030 V:|-(0)-[UITableView:0x1cbd9000]   (Names: '|':UIView:0x1d1aac20 )>",
    "<NSLayoutConstraint:0x1d1921d0 V:[UILabel:0x1c58f100]-(1)-[UIButton:0x1d1d1bb0]>",
    "<NSAutoresizingMaskLayoutConstraint:0x1c58e4d0 h=--- v=--- V:[UIWindow:0x1d002230(480)]>",
    "<NSLayoutConstraint:0x1d1cd6c0 V:[UITableView:0x1cbd9000]-(NSSpace(8))-[UILabel:0x1c58f100]>",
    "<NSLayoutConstraint:0x1d1ca370 V:[UIButton:0x1d1d1bb0]-(5)-|   (Names: '|':UIView:0x1d1aac20 )>",
    "<NSAutoresizingMaskLayoutConstraint:0x1d172a90 h=--& v=-&- UITransitionView:0x1d174220.height == UIWindow:0x1d002230.height>"
)
Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x1d1ce780 V:[UITableView:0x1cbd9000(469)]>
Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

在iPhone Retina 4英寸iOS 6上运行良好

Answer 1

问题是你在表视图上指定了一个垂直约束，将其高度绑定到469 pt。因为你想要那个表视图的高度是灵活的，你不想要那个约束。

Answer 2

NSLayoutConstraint仅在iOS 6中支持。

iPhone 3不支持iOS 6。3g是最早的模型