问如何将NSArray转换为NSMutableArray

EN

ABAddressBookRef addressBook = ABAddressBookCreate();
CFArrayRef allPeople = ABAddressBookCopyArrayOfAllPeople(addressBook);  
CFIndex nPeople = ABAddressBookGetPersonCount(addressBook);

NSMutableArray *tempPeoples=[[NSMutableArray alloc]init];

for(int i=0;i<nPeople;i++){

    ABRecordRef i1=CFArrayGetValueAtIndex(allPeople, i);
    [tempPeoples addObject:i1];

//  [peoples addObject:i1];

}// end of the for loop
peoples=[tempPeoples copy];