I get a error when i decode html entites using NSAttributedString. I use Swift 5. I want only html to string. I don't want webview.
SwiftUI Text
Text("It's a party!".decoded)
String Extension
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
}
}
Error Log
== 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)
NSAttributedString processes the run loop when it parses HTML. You can see it at the call to CFRUnLoopRunSpecific inside of the call to initWithData:. This is a very old problem with NSAttributedString. (I think I first encountered it around OS X 10.5, but I'm sure it's older than that.)
Because it processes the run loop, all kinds of things can happen in the middle of evaluating an HTML string. Timers can fire. Delayed selectors can be called. And in SwiftUI, that means that the UI might try to update. It's a mess. And it generates race conditions inside of apparently safe code. You're actually a bit lucky that Swift catches this kind of problem and crashes. The other common symptoms are even harder to debug ("impossible" deadlocks due to code reentrance is the most common I've encountered).
The short answer is that it's not safe to use NSAttributedString to evaluate HTML synchronously. The docs don't warn you about this, and the name of the method gives no hint about it. But you can't. Some folks will tell you to just make sure you evaluate this on the main thread, but even that doesn't guarantee you won't have really bizarre reentrance bugs if you have anything else pending on the run loop.
You'll need to evaluate this string another way. For example, see Martin R's answer to How do I decode HTML entities in Swift?
For a quick example of how even running this on the main thread can get you in trouble, consider the following code:
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's a party!".decoded)
}
// somewhere on the main queue. There's no background threads needed
dothing()
This outputs:
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!
If delayed mutates any state, then things may change out from under you, even though everything is on the main thread.
(The weird error is there because I tested this in didFinishLaunching, and that means that the runloop gets processed before the app finishes launching. That's exactly the kind of bugs you get with this.)