Description
We need a public API to add and remove view types from the subtree traversal in the SentryUIRedactBuilder:
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private func isViewSubtreeIgnored(_ view: UIView) -> Bool { |
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// We intentionally avoid using `NSClassFromString` or directly referencing class objects here, |
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// because both approaches can trigger the Objective-C `+initialize` method on the class. |
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// This has side effects and can cause crashes, especially when performed off the main thread |
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// or with UIKit classes that expect to be initialized on the main thread. |
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// |
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// Instead, we use the string description of the type (i.e., `type(of: view).description()`) |
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// for comparison. This is a safer, more "Swifty" approach that avoids the pitfalls of |
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// class initialization side effects. |
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// |
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// We have previously encountered related issues: |
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// - In EmergeTools' snapshotting code where using `NSClassFromString` led to crashes [1] |
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// - In Sentry's own SubClassFinder where storing or accessing class objects on a background thread caused crashes due to `+initialize` being called on UIKit classes [2] |
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// |
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// [1] https://github.com/EmergeTools/SnapshotPreviews/blob/main/Sources/SnapshotPreviewsCore/View%2BSnapshot.swift#L248 |
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// [2] https://github.com/getsentry/sentry-cocoa/blob/00d97404946a37e983eabb21cc64bd3d5d2cb474/Sources/Sentry/SentrySubClassFinder.m#L58-L84 |
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let viewTypeId = type(of: view).description() |
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if #available(iOS 26.0, *), viewTypeId == Self.cameraSwiftUIViewClassId.classId { |
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// CameraUI.ChromeSwiftUIView is a special case because it contains layers which can not be iterated due to this error: |
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// |
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// Fatal error: Use of unimplemented initializer 'init(layer:)' for class 'CameraUI.ModeLoupeLayer' |
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// |
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// This crash only occurs when building with Xcode 16 for iOS 26, so we add a runtime check |
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return true |
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} |
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#if os(iOS) |
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// UISwitch uses UIImageView internally, which can be in the list of redacted views. |
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// But UISwitch is in the list of ignored class identifiers by default, because it uses |
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// non-sensitive images. Therefore we want to ignore the subtree of UISwitch, unless |
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// it was removed from the list of ignored classes |
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if viewTypeId == "UISwitch" && containsIgnoreClassId(ClassIdentifier(classId: viewTypeId)) { |
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return true |
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} |
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#endif // os(iOS) |
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return false |
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} |
It will allow SDK users to extend the list of views, in case they are experiencing crashes caused by the view traversal, e.g. activating internal animations for CoreAnimation.
Example:
Application Specific Information:
-[NSConcreteValue doubleValue]: unrecognized selector sent to instance 0x1409e0cc0
Thread 0 Crashed:
0 CoreFoundation 0x3252a1994 __exceptionPreprocess
1 libobjc.A.dylib 0x31f169810 objc_exception_throw
2 CoreFoundation 0x32533a8fc -[NSObject(NSObject) doesNotRecognizeSelector:]
3 CoreFoundation 0x325221358 ___forwarding___
4 CoreFoundation 0x3252291fc __forwarding_prep_0___
5 QuartzCore 0x326843c68 -[NSNumber(CAAnimatableValue) CA_interpolateValue:byFraction:]
6 QuartzCore 0x32683f99c -[CABasicAnimation applyForTime:presentationObject:modelObject:]
7 QuartzCore 0x3265f98bc CA::Layer::presentation_layer
8 QuartzCore 0x3265f4008 CA::Layer::sublayers
9 MyApp 0x200a98d40 SentryUIRedactBuilder.mapRedactRegion
10 MyApp. 0x200a98ed4 [inlined] SentryUIRedactBuilder.mapRedactRegion
A reference for similar options is the list of masked and unmasked view classes in the session replay options:
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/** |
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* A list of custom UIView subclasses that need |
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* to be masked during session replay. |
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* By default Sentry already mask text and image elements from UIKit |
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* Every child of a view that is redacted will also be redacted. |
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* |
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* - Note: See ``SentryReplayOptions.DefaultValues.maskedViewClasses`` for the default value. |
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*/ |
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public var maskedViewClasses: [AnyClass] |
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/** |
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* A list of custom UIView subclasses to be ignored |
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* during masking step of the session replay. |
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* The views of given classes will not be redacted but their children may be. |
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* This property has precedence over `redactViewTypes`. |
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* |
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* - Note: See ``SentryReplayOptions.DefaultValues.unmaskedViewClasses`` for the default value. |
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*/ |
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public var unmaskedViewClasses: [AnyClass] |
We want to offer the SDK users to add additional view types, while also removing ours pre-defined ones (for flexibility), which is the CameraUI.ChromeSwiftUIView at this point in time only.
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/// Class identifier for ``CameraUI.ChromeSwiftUIView``, if it exists. |
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/// |
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/// This object identifier is used to identify views of this class type during the redaction process. |
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/// This workaround is specifically for Xcode 16 building for iOS 26 where accessing CameraUI.ModeLoupeLayer |
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/// causes a crash due to unimplemented init(layer:) initializer. |
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private static let cameraSwiftUIViewClassId = ClassIdentifier(classId: "CameraUI.ChromeSwiftUIView") |
Therefore, define the list should be a private field on the SentryReplayOptions.swift with two public helper methods includeSubtreeTraversalForViewType(String) and excludeSubtreeTraversalForViewType(String). The given string value will be compared to type(of: view).description().
