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我從底部佈局得到一些約束相對約束的問題。 UITabBarViewController中有一些視圖。當我從選項卡切換到另一個視圖並返回到第一個視圖時，viewcontroller不會將底部佈局識別爲選項卡欄，而是從視圖底部識別。底部佈局約束問題
我在這裏上傳的問題：https://sites.google.com/site/rveducationapps/layoutError.png?attredirects=0&d=1
我已經嘗試過把在ViewDidAppear也viewWillAppear中：
[self.view layoutSubviews];
[self.view setNeedsUpdateConstraints];
我登錄子視圖在兩種情況下，正確的，之後我退出和返回給視圖：
subviews:(
"<UIView: 0x146b2260; frame = (210 0; 814 712); autoresize = RM+BM; layer = <CALayer: 0x146b22c0>>",
"<UIButton: 0x146a9eb0; frame = (727 672; 287 30); opaque = NO; autoresize = RM+BM; layer = <CALayer: 0x146aa070>>",
"<UITableView: 0x151d3400; frame = (0 0; 210 761); clipsToBounds = YES; autoresize = W+H; gestureRecognizers = <NSArray: 0x146b14b0>; layer = <CALayer: 0x146ade20>; contentOffset: {0, 0}>",
"<_UILayoutGuide: 0x146b23b0; frame = (0 0; 0 20); hidden = YES; layer = <CALayer: 0x146b24a0>>",
"<_UILayoutGuide: 0x146b28a0; frame = (0 712; 0 56); hidden = YES; layer = <CALayer: 0x146b2910>>"
）
subviews:(
"<UIView: 0x146b2260; frame = (210 0; 814 768); autoresize = RM+BM; layer = <CALayer: 0x146b22c0>>",
"<UIButton: 0x146a9eb0; frame = (727 728; 287 30); opaque = NO; autoresize = RM+BM; layer = <CALayer: 0x146aa070>>",
"<UITableView: 0x151d3400; frame = (0 0; 210 817); clipsToBounds = YES; autoresize = W+H; gestureRecognizers = <NSArray: 0x146b14b0>; layer = <CALayer: 0x146ade20>; contentOffset: {0, 0}>",
"<_UILayoutGuide: 0x146b23b0; frame = (0 0; 0 20); hidden = YES; layer = <CALayer: 0x146b24a0>>",
"<_UILayoutGuide: 0x146b28a0; frame = (0 768; 0 0); hidden = YES; layer = <CALayer: 0x146b2910>>"
）
我看到有一些差異，特別是在："<_UILayoutGuide: 0x146b28a0; frame = (0 712; 0 56); hidden = YES; layer = <CALayer: 0x146b2910>>"
但我不知道如何解決它。
編輯： 我想我修好了。我選擇了Storyboard中的UIViewController，並禁用了EXTEND EDGES-> Under Bottom Bars選項。