Wrong behaviour of NSArray on arm64 (but works on x86_64)

[teticio]

Problem:
The NSArray contains only the first element of the list on the iPhone. The NSArray is correctly set to the full list on the iPhone emulator however.

iPhone 7: iOS 1.14.1
iPhone 8 emulator: iOS 1.14

main.py:

import kivy
from kivy.app import App
from kivy.uix.label import Label
from pyobjus import autoclass, objc_arr

NSArray = autoclass('NSArray')

class MyApp(App):

    def build(self):
        shape = [1, 96, 216, 1]
        array = NSArray.arrayWithObjects_(*shape + [None])
        output_shape = [
            array.objectAtIndex_(_).intValue()
            for _ in range(array.count())
        ]
        return Label(text=f'{output_shape}')


if __name__ == '__main__':
    MyApp().run()

relevant parts of buildozer.spec:

requirements = python3,kivy,pyobjus
ios.kivy_ios_url = https://github.com/kivy/kivy-ios
ios.kivy_ios_branch = master
ios.ios_deploy_url = https://github.com/phonegap/ios-deploy
ios.ios_deploy_branch = 1.10.0

Any ideas? I am trying to set the shape of a tensor for TensorFlow Lite and I have tried everything I can think of - even casting to a ctypes pointer to ints. I'd be very grateful for any pointers (no pun intended) or workarounds. Thanks!

[misl6]

Hi @teticio

NSArray.arrayWithObjects: is a variadic function, and should be prepared accordingly before calling it via ffi.

(We should use ffi_prep_cif_var instead of ffi_prep_cif over here if the function is variadic):

pyobjus/pyobjus/pyobjus.pyx

Line 320 in ea4ef7c

f_status = ffi_prep_cif(&self.f_cif, FFI_DEFAULT_ABI,

Unfortunately, (AFAIK) We don't have a proper way to distinguish a variadic function by looking at its signature.

Maybe We can add a list of function that We know that are variadic, or let the user to force it as variadic? What do you think about it @tito? Seems reasonable?

Meanwhile, as a workaround, you can easely populate the array by doing something like that:

NSMutableArray = autoclass("NSMutableArray")
NSArray = autoclass("NSArray")

mutarray = NSMutableArray.new()

for x in [1, 96, 216, 1]:
    mutarray.addObject_(x)

array = NSArray.arrayWithArray_(mutarray)
        
output_shape = [
     array.objectAtIndex_(_).intValue()
      for _ in range(array.count())
 ]
        
print(output_shape)

[teticio]

Thanks for this! Funnily enough, I was just reading through the Pyobjus documentation again and I had the same idea for a workaround and I just came back here to grab my code to try it out. Good to know!

[misl6]

Fixed via #85