NSMutableArray到NSArray排序

Question

i'm trying to sort my core data object by date. but i keep getting this error:

incompatible pointer types assigning to 'nsmutablearray *' from 'nsarray *'    

This is the code that i've made. All my other code is based on a nsmutablearray, so its important the output is a nsmutablearray. How can i do this without getting the error above?

devices = [devices2 sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"created" ascending:YES]]];

Answer 1

you can use mutableCopy function. So like

 devices = [[devices2 sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"created" ascending:YES]]] mutableCopy];

Answer 2

NSMutableArray has an alternative to sortedArrayUsingDescriptors , which sorts the array in place, instead of returning a new immutable array.

You can use:

[devices2 sortUsingDescriptors:@[ [NSSortDescriptor sortDescriptorWithKey:@"created" ascending:YES] ]];

Otherwise, as @Ethan stated above, you can create a mutableCopy of the resulting array.