我目前在Flurry的特定代码行中收到了一些崩溃报告：
var hasSeenConnectionPrompt = NSUserDefaults.standardUserDefaults().objectForKey("has-seen-connection-prompt") as? Bool ?? false
我无法复制，我在第一次编写代码时假设，如果已经看到连接提示＆＃39;为零，表达式将返回false。
有人能说清楚为什么会崩溃吗？
堆栈跟踪（xxxxxx是应用名称）：
0 xxxxxxxx 0x0014e628 showConnectionAlertFirstTimeOnly + 3920 (FullProfileView.swift:100)
1 xxxxxxxx 0x0014d66c onIntroduce + 2140 (FullProfileView.swift:95)
2 CoreFoundation 0x2be874a1 <redacted> + 12
3 CoreFoundation 0x2bde393d __CFXNotificationPost + 1784
4 Foundation 0x2cb139b9 -[NSNotificationCenter postNotificationName:object:userInfo:] + 72
5 Foundation 0x2cb1851f -[NSNotificationCenter postNotificationName:object:] + 30
6 xxxxxxxx 0x000f16c8 init + 3520 (MainViewController.swift:86)
7 xxxxxxxx 0x000f0df4 init + 1260 (MainViewController.swift:0)
8 xxxxxxxx 0x000f0e54 init + 1356 (MainViewController.swift:0)
9 UIKit 0x2f636e13 -[UIPresentationController transitionDidFinish:] + 1166
10 UIKit 0x2f9c12d1 -[_UIFullscreenPresentationController transitionDidFinish:] + 48
11 UIKit 0x2f639017 <redacted> + 150
12 UIKit 0x2f47d257 -[_UIViewControllerTransitionContext completeTransition:] + 102
13 UIKit 0x2f47d0fb -[UITransitionView notifyDidCompleteTransition:] + 294
14 UIKit 0x2f47cbe9 -[UITransitionView _didCompleteTransition:] + 968
15 UIKit 0x2f3a0845 -[UIViewAnimationState sendDelegateAnimationDidStop:finished:] + 184
16 UIKit 0x2f3a0757 -[UIViewAnimationState animationDidStop:finished:] + 66
17 QuartzCore 0x2ed99599 <redacted> + 236
18 libdispatch.dylib 0x39adc8b7 <redacted> + 22
19 libdispatch.dylib 0x39ae00bf __dispatch_main_queue_callback_4CF + 722
20 CoreFoundation 0x2be94be9 <redacted> + 8
21 CoreFoundation 0x2be932e9 <redacted> + 1512
22 CoreFoundation 0x2bde1621 _CFRunLoopRunSpecific + 476
23 CoreFoundation 0x2bde1433 _CFRunLoopRunInMode + 106
24 GraphicsServices 0x331900a9 _GSEventRunModal + 136
25 UIKit 0x2f3cc359 _UIApplicationMain + 1440
26 xxxxxxxx 0x00125624 init + 2060 (AppDelegate.swift:5)
27 libdyld.dylib 0x39afcaaf <redacted> + 2