Crash on App Start-Up

Question

Created Jan ’22

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I need help debugging an issue where the app I am developing crashes on start-up about once every five or six times I start it. The line of code that crashes is this:

page[pageToSet].parameter[parameterToSet].source = source

both the [parameterToSet].source and local "source" variable are defined as Strings and the value of "source" is "i ". This should be fine, yet, it crashes.

I followed xCode's recommendation to, "set a breakpoint in malloc_error_break to debug" and the next time my app crashed it reported:

libsystem_malloc.dylib`malloc_error_break:

-> 0x19d215cd8 <+0>: pacibsp 0x19d215cdc <+4>: stp x29, x30, [sp, #-0x10]! 0x19d215ce0 <+8>: mov x29, sp 0x19d215ce4 <+12>: nop 0x19d215ce8 <+16>: ldp x29, x30, [sp], #0x10 0x19d215cec <+20>: retab

Which is gibberish to me...

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Answer 1

Graphics and Games Engineer OP

Apple

Jan ’22

Hi, have you taken a look at a crash log for your app? Sometimes those contain additional info about the crash. You can find info about getting crash logs from iOS here.

Alternatively, you could add in assert statements to ensure that your dictionaries are not nil and that the keys are contained within the dictionary. Also, how is pageToSet generated?

It looks like the pacibsp instruction is a pointer authentication instruction https://developer.arm.com/documentation/dui0801/h/mpg1476202746202

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Answer 2

Herksrule OP

Jan ’22

"pageToSet" and "parameterToSet" are passed in as integers. I checked their values when the code crashes and both are valid numbers (pageToSet is 2, parameterToSet is 1, and source is "i "). Next time it blows up I'll try and get the crash log. Here is the whole function:

public func updateParameterStatus(pageToSet: Int, parameterToSet: Int, source: String){

if (pageToSet >= 1) && (pageToSet <= 10) && (parameterToSet >= 1) && (parameterToSet <= 20){

page[pageToSet].parameter[parameterToSet].source = source // this line crashes sometimes on start up for some reason

if source == "t "{ page[pageToSet].parameter[parameterToSet].isComputed = true } else { page[pageToSet].parameter[parameterToSet].isComputed = false }

page[pageToSet].parameter[parameterToSet].timeStamp = N777.currentTime.timeIntervalSinceReferenceDate page[pageToSet].parameter[parameterToSet].isValid = true page[pageToSet].parameter[parameterToSet].isStale = false

if source == "i " || source == "d " { page[pageToSet].parameter[parameterToSet].isImported = true } else { page[pageToSet].parameter[parameterToSet].isImported = false }

page[pageToSet].parameter[parameterToSet].hasBeenEntered = true } }

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