那些遇到过的问题

SwiftUI 解码 HTML 实体错误：同时访问 0x7ff43ff29b50，但修改需要独占访问

Asi*_*LAN 4 decode swiftui

当我使用 解码 html entites 时出现错误NSAttributedString。我使用 Swift 5。我只想将 html 字符串化。我不想要网络视图。

SwiftUI 文本

Text("It&#39s a party!".decoded)
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字符串扩展

extension String {
    var decoded: String {
        let attr = try? NSAttributedString(data: Data(utf8), options: [
        .documentType: NSAttributedString.DocumentType.html,
        .characterEncoding: String.Encoding.utf8.rawValue
    ], documentAttributes: nil)

        return attr?.string ?? self
    }
}
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错误日志

== AttributeGraph: cycle detected through attribute 123464 ===
=== AttributeGraph: cycle detected through attribute 143224 ===
=== AttributeGraph: cycle detected through attribute 128744 ===
Simultaneous accesses to 0x7ff43ff29b50, but modification requires exclusive access.
Previous access (a modification) started at SwiftUI`LayoutComputer.EngineDelegate.spacing() + 44 (0x7fff566b85dc).
Current access (a modification) started at:
0    libswiftCore.dylib                 0x00007fff2f41fe90 swift_beginAccess + 568
1    SwiftUI                            0x00007fff566b85b0 LayoutComputer.EngineDelegate.spacing() + 44
2    SwiftUI                            0x00007fff56657140 accumulateSpacing #1 (ofChild:) in StackLayout.Header.init(layoutContext:proxies:majorAxis:minorAxisAlignment:uniformSpacing:childStorage:capacity:resizeChildrenWithTrailingOverflow:) + 289
3    SwiftUI                            0x00007fff56656bf0 StackLayout.Header.init(layoutContext:proxies:majorAxis:minorAxisAlignment:uniformSpacing:childStorage:capacity:resizeChildrenWithTrailingOverflow:) + 414
4    SwiftUI                            0x00007fff561d9d00 specialized ManagedBufferPointer.init(bufferClass:minimumCapacity:makingHeaderWith:) + 296
5    SwiftUI                            0x00007fff561da140 specialized closure #2 in HVStack.updateLayoutComputer<A>(rule:layoutContext:children:) + 142
6    SwiftUI                            0x00007fff5626cce0 specialized closure #2 in HVStack.updateLayoutComputer<A>(rule:layoutContext:children:) + 41
7    SwiftUI                            0x00007fff56278590 partial apply for specialized closure #2 in HVStack.updateLayoutComputer<A>(rule:layoutContext:children:) + 43
8    SwiftUI                            0x00007fff561da3e0 specialized static LayoutComputerDelegate.update<A>(_:maybeInPlace:create:) + 136
9    SwiftUI                            0x00007fff56139060 specialized StatefulRule<>.updateLayoutComputer<A>(layout:environment:layoutComputers:) + 176
10   SwiftUI                            0x00007fff562692a0 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 236
11   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
12   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
13   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
14   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
15   SwiftUI                            0x00007fff56030ec0 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 32
16   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
17   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
18   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
19   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
20   SwiftUI                            0x00007fff56438660 DynamicLayoutViewChildGeometry.childGeometries.getter + 53
21   SwiftUI                            0x00007fff56438740 DynamicLayoutViewChildGeometry.updateValue() + 201
22   SwiftUI                            0x00007fff5626e730 partial apply for specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 15
23   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
24   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
25   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
26   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
27   SwiftUI                            0x00007fff55f66120 specialized UnaryChildGeometry.parentSize.getter + 28
28   SwiftUI                            0x00007fff55f66920 specialized UnaryChildGeometry.value.getter + 91
29   SwiftUI                            0x00007fff56035830 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 28
30   SwiftUI                            0x00007fff5605a690 partial apply for specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 20
31   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
32   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
33   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
34   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
35   SwiftUI                            0x00007fff55f66120 specialized UnaryChildGeometry.parentSize.getter + 28
36   SwiftUI                            0x00007fff55f666b0 specialized UnaryChildGeometry.value.getter + 91
37   SwiftUI                            0x00007fff56035830 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 28
38   SwiftUI                            0x00007fff56040ed0 partial apply for specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 20
39   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
40   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
41   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
42   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
43   SwiftUI                            0x00007fff55f66120 specialized UnaryChildGeometry.parentSize.getter + 28
44   SwiftUI                            0x00007fff55f666b0 specialized UnaryChildGeometry.value.getter + 91
45   SwiftUI                            0x00007fff56035830 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 28
46   SwiftUI                            0x00007fff56040ed0 partial apply for specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 20
47   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
48   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
49   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
50   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
51   SwiftUI                            0x00007fff55f66120 specialized UnaryChildGeometry.parentSize.getter + 28
52   SwiftUI                            0x00007fff55f66440 specialized UnaryChildGeometry.value.getter + 91
53   SwiftUI                            0x00007fff56035830 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 28
54   SwiftUI                            0x00007fff5604f800 partial apply for specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 20
55   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
56   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
57   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
58   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
59   SwiftUI                            0x00007fff55f66120 specialized UnaryChildGeometry.parentSize.getter + 28
60   SwiftUI                            0x00007fff55f666b0 specialized UnaryChildGeometry.value.getter + 91
61   SwiftUI                            0x00007fff56035830 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 28
62   SwiftUI                            0x00007fff56040ed0 partial apply for specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 20
63   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
64   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
65   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
66   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
67   SwiftUI                            0x00007fff56030ec0 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 55
68   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
69   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
70   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
71   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
72   SwiftUI                            0x00007fff56438660 DynamicLayoutViewChildGeometry.childGeometries.getter + 53
73   SwiftUI                            0x00007fff56438740 DynamicLayoutViewChildGeometry.updateValue() + 201
74   SwiftUI                            0x00007fff5626e730 partial apply for specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 15
75   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
76   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
77   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
78   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
79   SwiftUI                            0x00007fff56030ec0 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 55
80   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
81   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
82   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
83   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
84   SwiftUI                            0x00007fff56033ef0 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 63
85   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
86   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
87   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
88   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
89   SwiftUI                            0x00007fff568536f0 StyledTextChildGeometry.parentSize.getter + 27
90   SwiftUI                            0x00007fff560324b0 specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 41
91   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
92   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
93   AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
94   AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
95   SwiftUI                            0x00007fff5608cb10 LayoutPositionQuery.localPosition.getter + 22
96   SwiftUI                            0x00007fff5608cbd0 LayoutPositionQuery.updateValue() + 32
97   SwiftUI                            0x00007fff5628dab0 partial apply for specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 15
98   AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
99   AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
100  AttributeGraph                     0x00007fff4be8e654 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, AGSwiftMetadata const*, bool*, long) + 523
101  AttributeGraph                     0x00007fff4be9fcfa AGGraphGetValue + 203
102  SwiftUI                            0x00007fff568cd9e0 AnimatableFrameAttribute.updateValue() + 45
103  SwiftUI                            0x00007fff5628e5c0 partial apply for specialized implicit closure #2 in implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 15
104  AttributeGraph                     0x00007fff4be8952a AG::Graph::UpdateStack::update() + 505
105  AttributeGraph                     0x00007fff4be89a6a AG::Graph::update_attribute(AG::data::ptr<AG::Node>, bool) + 335
106  AttributeGraph                     0x00007fff4be91884 AG::Subgraph::update(unsigned int) + 781
107  SwiftUI                            0x00007fff5693a5f0 GraphHost.runTransaction() + 186
108  SwiftUI                            0x00007fff5640e3c0 ViewGraph.updateOutputs(at:) + 90
109  SwiftUI                            0x00007fff5689a880 closure #1 in ViewRendererHost.render(interval:updateDisplayList:) + 1305
110  SwiftUI                            0x00007fff5688dc20 ViewRendererHost.render(interval:updateDisplayList:) + 340
111  SwiftUI                            0x00007fff56a0a640 _UIHostingView.layoutSubviews() + 241
112  SwiftUI                            0x00007fff56a0a740 @objc _UIHostingView.layoutSubviews() + 21
113  UIKitCore                          0x00007fff24bd69a0 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2924
114  QuartzCore                         0x00007fff27a7708d -[CALayer layoutSublayers] + 258
115  QuartzCore                         0x00007fff27a7d402 CA::Layer::layout_if_needed(CA::Transaction*) + 575
116  QuartzCore                         0x00007fff27a89358 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 65
117  QuartzCore                         0x00007fff279c8f24 CA::Context::commit_transaction(CA::Transaction*, double, double*) + 496
118  QuartzCore                         0x00007fff279ffba0 CA::Transaction::commit() + 783
119  QuartzCore                         0x00007fff27a0101c CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 79
120  CoreFoundation                     0x00007fff2038b1d1 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
121  CoreFoundation                     0x00007fff20385844 __CFRunLoopDoObservers + 547
122  CoreFoundation                     0x00007fff2038548f CFRunLoopRunSpecific + 691
123  UIFoundation                       0x00007fff23a483bd -[NSHTMLReader _loadUsingWebKit] + 1847
124  UIFoundation                       0x00007fff23a49a13 -[NSHTMLReader attributedString] + 22
125  UIFoundation                       0x00007fff239c835a _NSReadAttributedStringFromURLOrData + 9439
126  UIFoundation                       0x00007fff239c8255 -[NSAttributedString(NSAttributedStringUIFoundationAdditions) initWithData:options:documentAttributes:error:] + 144
(lldb)
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Rob*_*ier 7

NSAttributedString 在解析 HTML 时处理运行循环。您可以在对 的调用内对 CFRUnLoopRunSpecific 的调用中看到它initWithData:。这是 NSAttributedString 的一个非常老的问题。（我想我第一次遇到它是在 OS X 10.5 左右，但我确信它比那更旧。）

因为它处理运行循环，所以在评估 HTML 字符串的过程中可能会发生各种情况。定时器可以触发。可以调用延迟选择器。在 SwiftUI 中，这意味着 UI 可能会尝试更新。一团糟。它会在表面上安全的代码中生成竞争条件。实际上你有点幸运，Swift 发现了这种问题并崩溃了。其他常见症状甚至更难调试（由于代码重入而导致的“不可能”死锁是我遇到的最常见的情况）。

简而言之，使用 NSAttributedString 同步评估 HTML 是不安全的。文档不会警告您这一点，并且方法的名称也没有给出任何提示。但你不能。有些人会告诉您确保在主线程上对其进行评估，但即使这样也不能保证如果您在运行循环上还有其他待处理的事情，就不会出现真正奇怪的重入错误。

您需要以另一种方式评估该字符串。例如，请参阅Martin R对如何在 Swift 中解码 HTML 实体？

有关在主线程上运行它如何给您带来麻烦的快速示例，请考虑以下代码：

func delayed() {
    print("Should be last")
}

func dothing() {
    // Run this on the next runloop
    DispatchQueue.main.async { self.delayed() }

    // These should print in order
    print("Prints first")
    print("It&#39s a party!".decoded)
}

// somewhere on the main queue. There's no background threads needed
dothing()
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这输出：

Prints first
2020-12-20 22:16:07.976101-0500 test[84698:5693517] [plugin] AddInstanceForFactory: No factory registered for id <CFUUID 0x600000bb8520> F8BB1C28-BAE8-11D6-9C31-00039315CD46
Should be last
It's a party!
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如果delayed改变任何状态，那么即使一切都在主线程上，事情也可能会在你的控制下发生变化。

（出现奇怪的错误是因为我在 中对此进行了测试didFinishLaunching，这意味着运行循环在应用程序完成启动之前得到处理。这正是您遇到的错误。）

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