Crash with NSURL URLWithString

I am seeing crash reports with our users at this line of code

NSURL *url = [NSURL URLWithString:self->urlAddress];

self->urlAddress is never nil.

My understanding is that if self->urlAddress is malformed in someway then URLWithString should return nil but it seems to crash the thread as below.

Has anybody any suggestions as t what might be wrong?

Thread 3 name: Thread 3 Crashed: 0 CoreFoundation 0x00000001a73704a0 CFStringGetLength + 60 (CFInternal.h:889) 1 CoreFoundation 0x00000001a739b5b4 _CFURLCreateWithURLString + 84 (CFURL.c:2046) 2 Foundation 0x00000001a8635908 +[NSURL(NSURL) URLWithString:relativeToURL:] + 52 (NSURL.m:463) 3 Dubline 0x0000000102f3391c __58-[settingsAccountViewController reloadDublineSettingsPage]_block_invoke + 1024 (settingsAccountViewController.m:273) 4 CFNetwork 0x00000001a79f23dc __40-[__NSURLSessionLocal taskForClassInfo:]_block_invoke + 540 (LocalSession.mm:687) 5 CFNetwork 0x00000001a7a04768 __49-[__NSCFLocalSessionTask _task_onqueue_didFinish]_block_invoke + 244 (LocalSessionTask.mm:584) 6 libdispatch.dylib 0x00000001a6fb9a84 _dispatch_call_block_and_release + 32 (init.c:1466) 7 libdispatch.dylib 0x00000001a6fbb81c _dispatch_client_callout + 20 (object.m:559) 8 libdispatch.dylib 0x00000001a6fc3004 _dispatch_lane_serial_drain + 620 (inline_internal.h:2557) 9 libdispatch.dylib 0x00000001a6fc3c34 _dispatch_lane_invoke + 456 (queue.c:3862) 10 libdispatch.dylib 0x00000001a6fce4bc _dispatch_workloop_worker_thread + 764 (queue.c:6589) 11 libsystem_pthread.dylib 0x00000001f304a7a4 0x1f3047000 + 14244 12 libsystem_pthread.dylib 0x00000001f305174c 0x1f3047000 + 42828

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davemaj
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could you show more code, and show the url (unless it is a local file URL)? Did you try to access the URL directly ?

Doc says:

This method expects URLString to contain only characters that are allowed in a properly formed URL. All other characters must be properly percent escaped. Any percent-escaped characters are interpreted using UTF-8 encoding.

Is it the case ?

Posted by
Claude31
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  • Thanks Claude....Unfortunately I am only seeing these crashes via Xcode->Organiser->crashes from real users so I cannot see the actual String that caused the URL problem.

    There are two variable parts in the NSString which depend on what happened previously but these should be simple letters or numbers with no funny characters.

    But even if there were funny characters my expectation is that URLWithString would return nil ?

    —
    davemaj
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I have eventually "trapped" the contents of the NSString that was converted to a NSURL which causes a crash in a real customer site

I show it below...( For our customer privacy I've hidden our server replacing it with xxxxxx.xxxxx.xx below but they are just lowercase alphabetical characters)

If I run this myself now then I don't get a crash!!! SO for some reason this just occurred in the real customer at that time!!

Anybody got any ideas?

I am running this on Thread 2 in case that is a factor?

NSString *dave = @"https://xxxxxxxx.xxxxx.xx/test/gate/b8e23d6e5dcfb0d5025fcc928f55ac1d5ae6ed03/settings";

NSURL *url = [NSURL URLWithString:dave]; <--- Crashes here

Posted by
davemaj
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Just an update in case it helps anybody....

A function was called unexpectedly twice in quick succession leading to the NSSString being de-allocated before NSURL got to use it.

I put some defensive code in and it seems to have fixed it

Posted by
davemaj
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