Mac OS 是否从不同线程同时调用drawRect: 等显示方法？访问数据模型时不是很危险吗？
Does Mac OS call display methods such as drawRect: concurrently from different threads? Isn't that dangerous when accessing the data model?
我们有一个 NSTableRowView 的子类，它覆盖了 drawSelectionInRect:（它在内部由 drawRect: 调用）。此方法需要访问 NSManagedObjectContext，因此作为健全性检查，我们在那里断言我们在主线程中。现在事实证明，有时 Apple 从非主线程调用 drawRect（下面的堆栈跟踪示例）。这是否意味着它甚至可以从两个不同的线程同时执行此操作？ IE。我们在覆盖 drawRect: 和使用数据模型时必须自己处理线程安全？
错误：断言失败：[NSThread isMainThread]: (ZS_AppDelegate.m:1287)
(
0 tomedo_kunden 0x00000001008af46a -[ZS_AppDelegate loggedInUser] + 554
1 tomedo_kunden 0x00000001016feca7 +[Nutzer 登录用户] + 71
2 tomedo_kunden 0x0000000100f33397 +[ZSUserDefaults(MacOS) colorFromPreferences:] + 167
3 tomedo_kunden 0x00000001003d8265 -[Besuch(BesuchCategory) baseTextColor] + 101
4 tomedo_kunden 0x000000010071f846 -[ZSTableRowView drawSelectionInRect:] + 806
5 AppKit 0x00007fffd189d26c -[NSTableRowView drawRect:] + 242
6 AppKit 0x00007fffd184eba3 -[NSView(NSInternal) _recursive:displayRectIgnoringOpacity:inGraphicsContext:CGContext:topView:shouldChangeFontReferenceColor:] + 1318
7 AppKit 0x00007fffd184f053 -[NSView(NSInternal) _recursive:displayRectIgnoringOpacity:inGraphicsContext:CGContext:topView:shouldChangeFontReferenceColor:] + 2518
8 AppKit 0x00007fffd184e548 __46-[NSView(NSLayerKitGlue) drawLayer:inContext:]_block_invoke + 267
9 AppKit 0x00007fffd184e071 -[NSView(NSLayerKitGlue) _drawViewBackingLayer:inContext:drawingHandler:] + 1589
10 AppKit 0x00007fffd184da36 -[NSView(NSLayerKitGlue) drawLayer:inContext:] + 80
11 AppKit 0x00007fffd19839ff -[_NSBackingLayerContents drawLayer:inContext:] + 162
12 QuartzCore 0x00007fffd96a1e42 -[CALayer drawInContext:] + 257
13 应用程序套件 0x00007fffd19834d8 -[_NSTiledLayer drawTile:inContext:] + 624
14 AppKit 0x00007fffd198320e -[_NSTiledLayerContents drawLayer:inContext:] + 176
15 QuartzCore 0x00007fffd96a1e42 -[CALayer drawInContext:] + 257
16 AppKit 0x00007fffd1983155 -[NSTileLayer drawInContext:] + 169
17 石英核心 0x00007fffd9584a38 CABackingStoreUpdate_ + 3740
18 石英核 0x00007fffd96a1a3c ___ZN2CA5Layer8display_Ev_block_invoke + 75
19 石英核心 0x00007fffd96a169d _ZN2CA5Layer8display_Ev + 1803
20 AppKit 0x00007fffd198306c -[NSTileLayer 显示] + 119
21 石英核 0x00007fffd9695546 _ZN2CA5Layer17display_if_neededEPNS_11TransactionE + 572
22 石英核 0x00007fffd9695671 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 35
23 石英核 0x00007fffd968ae88 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 280
24 石英核心 0x00007fffd9581d55 _ZN2CA11Transaction6commitEv + 475
25 AppKit 0x00007fffd19701d9 __58-[_NSScrollingConcurrentVBLMonitor _updateScrollAnimation]_block_invoke + 972
26 AppKit 0x00007fffd196aa3a -[_NSScrollingConcurrentSharedData threadSafePropertyAccess:] + 44
27 应用程序套件 0x00007fffd196d127 -[_NSScrollingConcurrentVBLMonitor _updateScrollAnimation] + 672
28 应用程序套件 0x00007fffd196c84e -[_NSScrollingConcurrentVBLMonitor _synchronizeForVBLSerialNumber:timestamp:updateDuration:] + 561
29 AppKit 0x00007fffd196c5ad __42-[_NSScrollingConcurrentVBLMonitor 简历]_block_invoke + 218
30 AppKit 0x00007fffd196c4ca __45-[NSScreen(NSScreenUpdate) addUpdateHandler:]_block_invoke_2 + 212
31 libdispatch.dylib 0x000000010345ffcc _dispatch_client_callout + 8
32 libdispatch.dylib 0x0000000103476bca _dispatch_continuation_pop + 1025
33 libdispatch.dylib 0x000000010346c6bc _dispatch_source_latch_and_call + 195
34 libdispatch.dylib 0x0000000103462e15 _dispatch_source_invoke + 1106
35 libdispatch.dylib 0x00000001034768f0 _dispatch_continuation_pop + 295
36 libdispatch.dylib 0x000000010346deda _dispatch_async_redirect_invoke + 777
37 libdispatch.dylib 0x0000000103462247 _dispatch_root_queue_drain + 671
38 libdispatch.dylib 0x0000000103461f58 _dispatch_worker_thread3 + 114
39 libsystem_pthread.dylib 0x00000001034d78c2 _pthread_wqthread + 1299
40 libsystem_pthread.dylib 0x00000001034d739d start_wqthread + 13
)
NSView 子类可以在最近发布的 OS X 中并发绘制。可以通过覆盖 canDrawConcurrently 并返回 NO.
来关闭此行为
您可能会发现最好将视图与模型分开一点，并将要呈现的数据与 CoreData 管理的数据分开一点；将要呈现的数据提取到仅限本地的表示中，并让 AppKit 同时更新视图。
https://developer.apple.com/reference/appkit/nsview/1483425-candrawconcurrently
我们有一个 NSTableRowView 的子类，它覆盖了 drawSelectionInRect:（它在内部由 drawRect: 调用）。此方法需要访问 NSManagedObjectContext，因此作为健全性检查，我们在那里断言我们在主线程中。现在事实证明，有时 Apple 从非主线程调用 drawRect（下面的堆栈跟踪示例）。这是否意味着它甚至可以从两个不同的线程同时执行此操作？ IE。我们在覆盖 drawRect: 和使用数据模型时必须自己处理线程安全？
错误：断言失败：[NSThread isMainThread]: (ZS_AppDelegate.m:1287)
(
0 tomedo_kunden 0x00000001008af46a -[ZS_AppDelegate loggedInUser] + 554
1 tomedo_kunden 0x00000001016feca7 +[Nutzer 登录用户] + 71
2 tomedo_kunden 0x0000000100f33397 +[ZSUserDefaults(MacOS) colorFromPreferences:] + 167
3 tomedo_kunden 0x00000001003d8265 -[Besuch(BesuchCategory) baseTextColor] + 101
4 tomedo_kunden 0x000000010071f846 -[ZSTableRowView drawSelectionInRect:] + 806
5 AppKit 0x00007fffd189d26c -[NSTableRowView drawRect:] + 242
6 AppKit 0x00007fffd184eba3 -[NSView(NSInternal) _recursive:displayRectIgnoringOpacity:inGraphicsContext:CGContext:topView:shouldChangeFontReferenceColor:] + 1318
7 AppKit 0x00007fffd184f053 -[NSView(NSInternal) _recursive:displayRectIgnoringOpacity:inGraphicsContext:CGContext:topView:shouldChangeFontReferenceColor:] + 2518
8 AppKit 0x00007fffd184e548 __46-[NSView(NSLayerKitGlue) drawLayer:inContext:]_block_invoke + 267
9 AppKit 0x00007fffd184e071 -[NSView(NSLayerKitGlue) _drawViewBackingLayer:inContext:drawingHandler:] + 1589
10 AppKit 0x00007fffd184da36 -[NSView(NSLayerKitGlue) drawLayer:inContext:] + 80
11 AppKit 0x00007fffd19839ff -[_NSBackingLayerContents drawLayer:inContext:] + 162
12 QuartzCore 0x00007fffd96a1e42 -[CALayer drawInContext:] + 257
13 应用程序套件 0x00007fffd19834d8 -[_NSTiledLayer drawTile:inContext:] + 624
14 AppKit 0x00007fffd198320e -[_NSTiledLayerContents drawLayer:inContext:] + 176
15 QuartzCore 0x00007fffd96a1e42 -[CALayer drawInContext:] + 257
16 AppKit 0x00007fffd1983155 -[NSTileLayer drawInContext:] + 169
17 石英核心 0x00007fffd9584a38 CABackingStoreUpdate_ + 3740
18 石英核 0x00007fffd96a1a3c ___ZN2CA5Layer8display_Ev_block_invoke + 75
19 石英核心 0x00007fffd96a169d _ZN2CA5Layer8display_Ev + 1803
20 AppKit 0x00007fffd198306c -[NSTileLayer 显示] + 119
21 石英核 0x00007fffd9695546 _ZN2CA5Layer17display_if_neededEPNS_11TransactionE + 572
22 石英核 0x00007fffd9695671 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 35
23 石英核 0x00007fffd968ae88 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 280
24 石英核心 0x00007fffd9581d55 _ZN2CA11Transaction6commitEv + 475
25 AppKit 0x00007fffd19701d9 __58-[_NSScrollingConcurrentVBLMonitor _updateScrollAnimation]_block_invoke + 972
26 AppKit 0x00007fffd196aa3a -[_NSScrollingConcurrentSharedData threadSafePropertyAccess:] + 44
27 应用程序套件 0x00007fffd196d127 -[_NSScrollingConcurrentVBLMonitor _updateScrollAnimation] + 672
28 应用程序套件 0x00007fffd196c84e -[_NSScrollingConcurrentVBLMonitor _synchronizeForVBLSerialNumber:timestamp:updateDuration:] + 561
29 AppKit 0x00007fffd196c5ad __42-[_NSScrollingConcurrentVBLMonitor 简历]_block_invoke + 218
30 AppKit 0x00007fffd196c4ca __45-[NSScreen(NSScreenUpdate) addUpdateHandler:]_block_invoke_2 + 212
31 libdispatch.dylib 0x000000010345ffcc _dispatch_client_callout + 8
32 libdispatch.dylib 0x0000000103476bca _dispatch_continuation_pop + 1025
33 libdispatch.dylib 0x000000010346c6bc _dispatch_source_latch_and_call + 195
34 libdispatch.dylib 0x0000000103462e15 _dispatch_source_invoke + 1106
35 libdispatch.dylib 0x00000001034768f0 _dispatch_continuation_pop + 295
36 libdispatch.dylib 0x000000010346deda _dispatch_async_redirect_invoke + 777
37 libdispatch.dylib 0x0000000103462247 _dispatch_root_queue_drain + 671
38 libdispatch.dylib 0x0000000103461f58 _dispatch_worker_thread3 + 114
39 libsystem_pthread.dylib 0x00000001034d78c2 _pthread_wqthread + 1299
40 libsystem_pthread.dylib 0x00000001034d739d start_wqthread + 13
)
NSView 子类可以在最近发布的 OS X 中并发绘制。可以通过覆盖 canDrawConcurrently 并返回 NO.
您可能会发现最好将视图与模型分开一点，并将要呈现的数据与 CoreData 管理的数据分开一点；将要呈现的数据提取到仅限本地的表示中，并让 AppKit 同时更新视图。
https://developer.apple.com/reference/appkit/nsview/1483425-candrawconcurrently