Timestamp function that has been working reliably

问题:

I have been using this function to generate a time stamp. I found it somewhere here on Stack Overflow.

@objc public class var timestamp: String {
    return "\(Int(NSDate().timeIntervalSince1970 * 1000))"
}

It has been working without issue, but I just got a EXC_BAD_INSTRUCTION:

fatal error: floating point value cannot be converted to Int because it is greater than Int.max

As the development of this app is nearing completion it makes me nervous to all of the sudden see it cause a EXC_BAD_INSTRUCTION. This is running in the Simulator, but I have a valid date and time set.

Any ideas or suggestions or are greatly appreciated. Below is the backtrace.

(lldb) bt
* thread #1: tid = 0x15c4d, 0x04a30393 libswiftCore.dylib`function signature specialization <Arg[0] = Exploded, Arg[1] = Exploded, Arg[2] = Dead, Arg[3] = Dead> of Swift._fatalErrorMessage (Swift.StaticString, Swift.StaticString, Swift.StaticString, Swift.UInt) -> () + 67, queue = 'com.apple.main-thread', stop reason = EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
frame #0: 0x04a30393 libswiftCore.dylib function signature specialization <Arg[0] = Exploded, Arg[1] = Exploded, Arg[2] = Dead, Arg[3] = Dead> of Swift._fatalErrorMessage (Swift.StaticString, Swift.StaticString, Swift.StaticString, Swift.UInt) -> () + 67
* frame #1: 0x00afe0c9 TDTPhotoLib static     
TDTDeviceUtilites.timestamp.getter(self=TDTPhotoLib.TDTDeviceUtilites) + 409 at TDTDeviceUtilites.swift:127
frame #2: 0x00166979 Oilist TDTPaintingViewController.finshedSession(sender=0x7aee0fb0, self=0x7e9d3800) -> () + 169 at TDTPaintingViewController.swift:1370
frame #3: 0x00102896 Oilist TDTOilistMenuPainting.goForward(sender=0x7aee0fb0, self=0x7c218770) -> () + 374 at TDTOilistMenuPainting.swift:149
frame #4: 0x0010290d Oilist @objc TDTOilistMenuPainting.goForward(UIButton!) -> () + 61 at TDTOilistMenuPainting.swift:0
frame #5: 0x018a80b5 libobjc.A.dylib -[NSObject performSelector:withObject:withObject:] + 84
frame #6: 0x0336ee38 UIKit -[UIApplication sendAction:to:from:forEvent:] + 118
frame #7: 0x0336edb7 UIKit -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 64
frame #8: 0x03512f3b UIKit -[UIControl sendAction:to:forEvent:] + 79
frame #9: 0x035132d4 UIKit -[UIControl _sendActionsForEvents:withEvent:] + 433
frame #10: 0x035122c1 UIKit -[UIControl touchesEnded:withEvent:] + 714
frame #11: 0x033ef52e UIKit -[UIWindow _sendTouchesForEvent:] + 1095
frame #12: 0x033f05cc UIKit -[UIWindow sendEvent:] + 1159
frame #13: 0x03391be8 UIKit -[UIApplication sendEvent:] + 266
frame #14: 0x03366769 UIKit _UIApplicationHandleEventQueue + 7795
frame #15: 0x02423e5f CoreFoundation __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
frame #16: 0x02419aeb CoreFoundation __CFRunLoopDoSources0 + 523
frame #17: 0x02418f08 CoreFoundation __CFRunLoopRun + 1032
frame #18: 0x02418846 CoreFoundation CFRunLoopRunSpecific + 470
frame #19: 0x0241865b CoreFoundation CFRunLoopRunInMode + 123
frame #20: 0x07031664 GraphicsServices GSEventRunModal + 192
frame #21: 0x070314a1 GraphicsServices GSEventRun + 104
frame #22: 0x0336ceb9 UIKit UIApplicationMain + 160
frame #23: 0x00131ed1 Oilist main + 145 at AppDelegate.swift:14
frame #24: 0x05631a25 libdyld.dylib start + 1

回答1:

Your code will crash on all 32-bit platforms (such as iPhone 4, 5) because the result of

NSDate().timeIntervalSince1970 * 1000
// E.g.: 1464850525047.38

does not fit into a 32-bit integer. As a solution, use 64-bit integers:

Int64(NSDate().timeIntervalSince1970 * 1000)

Alternatively, if the intention is to create a string representing the milliseconds, use string formatting instead of an integer conversion:

String(format:"%.0f", NSDate().timeIntervalSince1970 * 1000)