1718449215 is the decimal representation of the four character code for the kAudioFormatUnsupportedDataFormatError
error.
In general you can use something like this to get more information from the errors you receive:
NSError *error = [NSError errorWithDomain:NSOSStatusErrorDomain
code:my_error_code
userInfo:nil];
NSLog(@"Error: %@", [error description]);
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