Objective C Quick Sort

quicksort

- (NSArray*) quickSortArray:(NSArray*) arr {
    
    if(arr.count <2) {
        return arr;
    }
    NSMutableArray *mutableArr = [arr mutableCopy];
    
 
    NSMutableArray *leftArray = [[NSMutableArray alloc] init];
	NSMutableArray *rightArray = [[NSMutableArray alloc] init];
	NSUInteger pivot = arr.count/2;
	NSNumber *pivotValue = [mutableArr objectAtIndex:pivot];
	
	[mutableArr removeObjectAtIndex:pivot];
	for(int i=0;i<mutableArr.count;i++) {
		NSNumber *val = [mutableArr objectAtIndex:i];
		if([val floatValue] < [pivotValue floatValue] ) {
			[leftArray addObject:val];
		} else {
			[rightArray addObject:val];
		}
    }
	
	leftArray = [[self quickSortArray:leftArray] mutableCopy];
	rightArray = [[self quickSortArray:rightArray ] mutableCopy];
    
	[leftArray addObject:pivotValue];
	[leftArray addObjectsFromArray:rightArray];
    return leftArray;
}