ios - 仅警告一次 : UITableView was told to layout its visible cells and other contents without being in the view hierarchy?

Question

我在 viewController 上添加了 tableView。
当我打开此屏幕时，我将收到以下警告一次。

[TableView] Warning once only: UITableView was told to layout itsvisible cells and other contents without being in the view hierarchy(the table view or one of its superviews has not been added to awindow). This may cause bugs by forcing views inside the table view toload and perform layout without accurate information (e.g. table viewbounds, trait collection, layout margins, safe area insets, etc), andwill also cause unnecessary performance overhead due to extra layoutpasses. Make a symbolic breakpoint atUITableViewAlertForLayoutOutsideViewHierarchy to catch this in thedebugger and see what caused this to occur, so you can avoid thisaction altogether if possible, or defer it until the table view hasbeen added to a window. Table view: <UITableView: 0x7fe2ba8d5a00;frame = (-47 -80; 394 553); clipsToBounds = YES; autoresize = RM+BM;gestureRecognizers = <NSArray: 0x600003447480>; layer = <CALayer:0x600003aa2be0>; contentOffset: {0, 0}; contentSize: {394, 176};adjustedContentInset: {0, 0, 0, 0}; dataSource:<Project.MondayToSundayViewController: 0x7fe2b9da05c0>>

当为 UITableViewAlertForLayoutOutsideViewHierarchy 添加符号断点时，控制台中会显示以下内容。

> UIKitCore`UITableViewAlertForLayoutOutsideViewHierarchy:
->  0x7fff48260c7e <+0>:   pushq  %rbp
    0x7fff48260c7f <+1>:   movq   %rsp, %rbp
    0x7fff48260c82 <+4>:   pushq  %r14
    0x7fff48260c84 <+6>:   pushq  %rbx
    0x7fff48260c85 <+7>:   subq   $0x30, %rsp
    0x7fff48260c89 <+11>:  callq  *0x3e51a6a1(%rip)         ; (void *)0x00007fff51411350: objc_retain
    0x7fff48260c8f <+17>:  movq   %rax, %rbx
    0x7fff48260c92 <+20>:  leaq   0x416a8dbf(%rip), %rdi    ; _UIInternalPreference_UITableViewEnableAlertForLayoutOutsideViewHierarchy
    0x7fff48260c99 <+27>:  leaq   0x3e5a2140(%rip), %rsi    ; @"UITableViewEnableAlertForLayoutOutsideViewHierarchy"
    0x7fff48260ca0 <+34>:  callq  0x7fff482a7529            ; _UIInternalPreferenceUsesDefault
    0x7fff48260ca5 <+39>:  testb  %al, %al
    0x7fff48260ca7 <+41>:  jne    0x7fff48260cb3            ; <+53>
    0x7fff48260ca9 <+43>:  movb   0x416a8dad(%rip), %al     ; _UIInternalPreference_UITableViewEnableAlertForLayoutOutsideViewHierarchy + 4
    0x7fff48260caf <+49>:  andb   $0x1, %al
    0x7fff48260cb1 <+51>:  je     0x7fff48260d2d            ; <+175>
    0x7fff48260cb3 <+53>:  leaq   0x416c3ffe(%rip), %rax    ; _UIApplicationLinkedOnVersion
    0x7fff48260cba <+60>:  movl   (%rax), %eax
    0x7fff48260cbc <+62>:  testl  %eax, %eax
    0x7fff48260cbe <+64>:  je     0x7fff48260d3e            ; <+192>
    0x7fff48260cc0 <+66>:  cmpl   $0xd0000, %eax            ; imm = 0xD0000 
    0x7fff48260cc5 <+71>:  jb     0x7fff48260d2d            ; <+175>
    0x7fff48260cc7 <+73>:  movq   %rbx, %rdi
    0x7fff48260cca <+76>:  callq  0x7fff486252fa            ; symbol stub for: objc_opt_class
    0x7fff48260ccf <+81>:  movq   0x41607402(%rip), %rsi    ; "_isInternalTableView"
    0x7fff48260cd6 <+88>:  movq   %rax, %rdi
    0x7fff48260cd9 <+91>:  callq  *0x3e51a641(%rip)         ; (void *)0x00007fff513f7780: objc_msgSend
    0x7fff48260cdf <+97>:  testb  %al, %al
    0x7fff48260ce1 <+99>:  jne    0x7fff48260d2d            ; <+175>
    0x7fff48260ce3 <+101>: movq   0x3e519b46(%rip), %rax    ; (void *)0x00007fff89ea06a0: _NSConcreteStackBlock
    0x7fff48260cea <+108>: movq   %rax, -0x38(%rbp)
    0x7fff48260cee <+112>: movl   $0xc2000000, %eax         ; imm = 0xC2000000 
    0x7fff48260cf3 <+117>: movq   %rax, -0x30(%rbp)
    0x7fff48260cf7 <+121>: leaq   0x46728(%rip), %rax       ; __UITableViewAlertForLayoutOutsideViewHierarchy_block_invoke
    0x7fff48260cfe <+128>: movq   %rax, -0x28(%rbp)
    0x7fff48260d02 <+132>: leaq   0x3e51d237(%rip), %rax    ; __block_descriptor_40_e8_32s_e5_v8?0l
    0x7fff48260d09 <+139>: movq   %rax, -0x20(%rbp)
    0x7fff48260d0d <+143>: movq   %rbx, %rdi
    0x7fff48260d10 <+146>: callq  *0x3e51a61a(%rip)         ; (void *)0x00007fff51411350: objc_retain
    0x7fff48260d16 <+152>: movq   %rax, -0x18(%rbp)
    0x7fff48260d1a <+156>: cmpq   $-0x1, 0x416ca5c6(%rip)   ; _UIInternalPreference_TableViewReorderingUsesDragAndDrop_block_invoke_10.__s_category + 7
    0x7fff48260d22 <+164>: jne    0x7fff48260d52            ; <+212>
    0x7fff48260d24 <+166>: movq   %rax, %rdi
    0x7fff48260d27 <+169>: callq  *0x3e51a5fb(%rip)         ; (void *)0x00007fff51411000: objc_release
    0x7fff48260d2d <+175>: movq   %rbx, %rdi
    0x7fff48260d30 <+178>: addq   $0x30, %rsp
    0x7fff48260d34 <+182>: popq   %rbx
    0x7fff48260d35 <+183>: popq   %r14
    0x7fff48260d37 <+185>: popq   %rbp
    0x7fff48260d38 <+186>: jmpq   *0x3e51a5ea(%rip)         ; (void *)0x00007fff51411000: objc_release
    0x7fff48260d3e <+192>: movl   $0xd0000, %edi            ; imm = 0xD0000 
    0x7fff48260d43 <+197>: callq  0x7fff48093724            ; _UIApplicationLinkedOnOrAfter
    0x7fff48260d48 <+202>: testb  %al, %al
    0x7fff48260d4a <+204>: jne    0x7fff48260cc7            ; <+73>
    0x7fff48260d50 <+210>: jmp    0x7fff48260d2d            ; <+175>
    0x7fff48260d52 <+212>: leaq   0x416ca58f(%rip), %rdi    ; UITableViewAlertForLayoutOutsideViewHierarchy.once
    0x7fff48260d59 <+219>: leaq   -0x38(%rbp), %r14
    0x7fff48260d5d <+223>: movq   %r14, %rsi
    0x7fff48260d60 <+226>: callq  0x7fff48624f8e            ; symbol stub for: dispatch_once
    0x7fff48260d65 <+231>: movq   0x20(%r14), %rax
    0x7fff48260d69 <+235>: jmp    0x7fff48260d24            ; <+166>

你能帮我删除警告吗？

Answer 1

在将 View 添加到 View 层次结构之前添加了约束。这就是您收到此错误的原因。
确保依次添加，例如:

view.addSubview(tableView) // 1
// 2 and start adding constraints..
tableView.translatesAutoresizingMaskIntoConstraints = false
...