// 非容器类对象
     NSString *str = @"origin string";
     NSString *strCopy = [str copy];
     NSMutableString *mstrCopy = [str mutableCopy];
     [mstrCopy appendString:@"??"];

NSMutableString *mstr = [NSMutableString stringWithString:@"origin"];
     NSString *strCopy = [mstr copy];
     NSMutableString *mstrCopy = [mstr copy];
     NSMutableString *mstrMCopy = [mstr mutableCopy];
     //[mstrCopy appendString:@"1111"];  //error
     [mstr appendString:@"222"];
     [mstrMCopy appendString:@"333"];

NSArray *array1     = [NSArray arrayWithObjects:@"a",@"b",@"c",nil];
     NSArray *arrayCopy1 = [array1 copy];
     //arrayCopy1是和array同一个NSArray对象（指向相同的对象），包括array里面的元素也是指向相同的指针
     NSLog(@"array1 retain count: %d",[array1 retainCount]);
     NSLog(@"array1 retain count: %d",[arrayCopy1 retainCount]);
     
     NSMutableArray *mArrayCopy1 = [array1 mutableCopy];
     //mArrayCopy1是array1的可变副本，指向的对象和array1不同，但是其中的元素和array1中的元素指向的还是同一个对象。mArrayCopy1还可以修改自己的对象
     [mArrayCopy1 addObject:@"de"];
     [mArrayCopy1 removeObjectAtIndex:0];

NSArray *mArray1 = [NSArray arrayWithObjects:[NSMutableString stringWithString:@"a"],@"b",@"c",nil];
     NSLog(@"mArray1 retain count: %d",[mArray1 retainCount]);
     NSArray *mArrayCopy2 = [mArray1 copy];
     NSLog(@"mArray1 retain count: %d",[mArray1 retainCount]);
     // mArray1和mArrayCopy2指向同一对象，retain值+1。
     
     NSMutableArray *mArrayMCopy1 = [mArray1 mutableCopy];
     NSLog(@"mArray1 retain count: %d",[mArray1 retainCount]);
     //mArrayCopy2和mArray1指向的是不一样的对象，但是其中的元素都是一样的对象——同一个指针

     NSMutableString *testString = [mArray1 objectAtIndex:0];
     //testString = @"1a1";//这样会改变testString的指针，其实是将@“1a1”临时对象赋给了testString
     [testString appendString:@" tail"];//这样以上三个数组的首元素都被改变了

NSArray *array = [NSArray arrayWithObjects:[NSMutableString stringWithString:@"first"],[NSStringstringWithString:@"b"],@"c",nil];
     NSArray *deepCopyArray=[[NSArray alloc] initWithArray: array copyItems: YES];
     NSArray* trueDeepCopyArray = [NSKeyedUnarchiver unarchiveObjectWithData:
     [NSKeyedArchiver archivedDataWithRootObject: array]];

#import

@interface NSDictionary(MutableDeepCopy)

- (NSMutableDictionary *)mutableDeepCopy;

@end
 <<span style="LINE-HEIGHT: 19px">/foundation>

#import "NSDictionaryMutableDeepCopy.h"


@implementation NSDictionary(MutableDeepCopy)

- (NSMutableDictionary *)mutableDeepCopy {
     NSMutableDictionary *ret = [[NSMutableDictionary alloc]
                                 initWithCapacity:[self count]];
     NSArray *keys = [self allKeys];
     for (id key in keys) {
         id oneValue = [self valueForKey:key];
         id oneCopy = nil;
         
         if ([oneValue respondsToSelector:@selector(mutableDeepCopy)]) {
             oneCopy = [oneValue mutableDeepCopy];
         }
         else if ([oneValue respondsToSelector:@selector(mutableCopy)]) {
             oneCopy = [oneValue mutableCopy];
         }
         if (oneCopy == nil) {
             oneCopy = [oneValue copy];
         }
         [ret setValue:oneCopy forKey:key];
     }
     
     return ret;
}

@end

@interface MyObj : NSObject
{
          NSMutableString *name;
          NSString *imutableStr;
          int age;
}
@property (nonatomic, retain) NSMutableString *name;
@property (nonatomic, retain) NSString *imutableStr;
@property (nonatomic) int age;
  
@end
  
@implementation MyObj
@synthesize name;
@synthesize age;
@synthesize imutableStr;
- (id)init
{
          if (self = [super init])
          {
                    self.name = [[NSMutableString alloc]init];
                    self.imutableStr = [[NSString alloc]init];
                    age = -1;
          }
          return self;
}
  
- (void)dealloc
{
          [name release];
          [imutableStr release];
          [super dealloc];
}
- (id)copyWithZone:(NSZone *)zone
{
          MyObj *copy = [[[self class] allocWithZone:zone] init];
          copy->name = [name copy];
          copy->imutableStr = [imutableStr copy];
//      
//      
          copy->age = age;
  
          return copy;
}
- (id)mutableCopyWithZone:(NSZone *)zone
{
          MyObj *copy = NSCopyObject(self, 0, zone);
          copy->name = [self.name mutableCopy];
          copy->age = age;
          return copy;
}
@end
 <<span style="LINE-HEIGHT: 19px">/nscopying