xcode - 为什么 NSFontManager.availableMembers(ofFontFamily :) crashing in Xcode 8 GM?

Question

我在 Xcode 8 Beta 6 (8S201h) 中写了这个:

guard let faceMembers = NSFontManager.shared().availableMembers(ofFontFamily: familyName ?? fontName) else { return nil }

而且效果很好。现在我已经升级到 Xcode 8 GM Seed (8A218a) Xcode 8 (8A218a)，它崩溃了 (EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0))。

使用调试器缩小它的范围，我发现 NSFontManager.availableMembers(ofFontFamily:) 中的某些东西真的很讨厌这个，因为无论我放在那里它都会崩溃，即使是普通的(绝对是安装!)像 Helvetica Neue 这样的字体。

(lldb) po NSFontManager.shared()
<NSFontManager: 0x6100000a24c0>

(lldb) po familyName
▿ Optional<String>
  - some : "Helvetica Neue"


(lldb) po fontName
"HelveticaNeue"


(lldb) po NSFontManager.shared().availableMembers(ofFontFamily: familyName ?? fontName)
error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).
The process has been returned to the state before expression evaluation.
(lldb) po NSFontManager.shared().availableMembers(ofFontFamily: familyName!)
error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).
The process has been returned to the state before expression evaluation.
(lldb) po NSFontManager.shared().availableMembers(ofFontFamily: "Not a real font?!")
nil

因此，当我向它传递一个有效的字体系列名称时，它会崩溃...但是当我向它传递一个假的字体系列名称时，它会返回 nil。

这是我可以解决的问题，还是只是 Xcode 8 GM Seed Xcode 8 的问题，将在 SDK 更新中解决？

---

查看崩溃日志后，我看到了这个可疑之处:

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libswiftFoundation.dylib        0x0000000107cbb249 _TZFE10FoundationSa26_forceBridgeFromObjectiveCfTCSo7NSArray6resultRGSqGSax___T_ + 153
1   libswiftCore.dylib              0x00000001079031f3 swift_dynamicCast + 1635
2   libswiftCore.dylib              0x000000010790448b _dynamicCastFromExistential(swift::OpaqueValue*, swift::OpaqueValue*, swift::TargetExistentialTypeMetadata<swift::InProcess> const*, swift::TargetMetadata<swift::InProcess> const*, swift::DynamicCastFlags) + 91
3   libswiftCore.dylib              0x0000000107903919 swift_dynamicCast + 3465
4   libswiftFoundation.dylib        0x0000000107d6a348 _TPA__TFFs15_arrayForceCastu0_rFGSax_GSaq__U_FQ_Q0_ + 56
5   libswiftFoundation.dylib        0x0000000107cbbc45 _TFEsPs10Collection3mapurfzFzWx8Iterator7Element_qd__GSaqd___ + 885
6   libswiftFoundation.dylib        0x0000000107cbb4c3 _TFs15_arrayForceCastu0_rFGSax_GSaq__ + 227
7   libswiftFoundation.dylib        0x0000000107cbb7a5 _TZFE10FoundationSa36_unconditionallyBridgeFromObjectiveCfGSqCSo7NSArray_GSax_ + 197

所以它似乎在 Swift-Foundation 中崩溃，在一些名为 _forceBridgeFromObjectiveC 的函数中...不确定这是否对任何人有帮助，但它确实确认它在 SDK/运行时中。

Answer 1

在此期间，我能弄清楚如何解决这个问题的唯一方法是在 objective-c 类中创建一个静态方法。然后，我将该 header 导入到我的桥接 header 中，并从 Swift 3 调用静态方法，它运行良好。

希望这能帮助您度过这些困难时期!

#import <Foundation/Foundation.h>
#import <Cocoa/Cocoa.h>

@interface WorkAround : NSObject

+ (NSArray *)typefacesForFontFamily:(NSString *)family;

@end


#import "WorkAround.h"

@implementation WorkAround

/// Returns an array of arrays, or nil, that contain information about
/// each typeface found for the specified font family.
+ (NSArray *)typefacesForFontFamily:(nonnull NSString *)family {
  NSFontManager *fontManager = [NSFontManager sharedFontManager];
  return [fontManager availableMembersOfFontFamily:family];
}
@end