ios开发（三）：deep copy

http://www.techotopia.com/index.php/Copying_Objects_in_Objective-C

下面是一个deep copy的例子：

NSString *myString1 = @"Hello";
NSString *myString2;

myString2 = [myString1 mutableCopy];

mac喜欢用mutable这个次来表示deep copy，且不支持运算符重载，所以所有的deep copy都要通过函数来实现，那我们自己如何实现deep copy呢？下面是一个例子，注意黑体部分。

@interface BankAccount: NSObject <NSCopying>
{
        double accountBalance;
        long accountNumber;
}
-(void) setAccount: (long) y andBalance: (double) x;
-(double) getAccountBalance;
-(long) getAccountNumber;
-(void) setAccountBalance: (double) x;
-(void) setAccountNumber: (long) y;
-(void) displayAccountInfo;
-(id) copyWithZone: (NSZone *) zone;
@end

-(id) copyWithZone: (NSZone *) zone
{
        BankAccount *accountCopy = [[BankAccount allocWithZone: zone] init];

        [accountCopy setAccount: accountNumber andBalance: accountBalance];
        return accountCopy;
}

int main (int argc, const char * argv[])
{
    @autoreleasepool {

        BankAccount *account1;
        BankAccount *account2;

        account1 = [BankAccount alloc];

        account1 = [account1 init];

        [account1 setAccountBalance: 1500.53];
        [account1 setAccountNumber: 34543212];

        [account1 displayAccountInfo];

        account2 = [account1 copy];

        [account2 displayAccountInfo];

    }
    return 0;
}

最后是一个array deep copy的例子：

NSArray *myArray1;
NSArray *myArray2;
NSMutableString *tmpStr;
NSMutableString *string1;
NSMutableString *string2;
NSMutableString *string3;
NSData *buffer;


string1 = [NSMutableString stringWithString: @"Red"];
string2 = [NSMutableString stringWithString: @"Green"];
string3 = [NSMutableString stringWithString: @"Blue"];

myArray1 = [NSMutableArray arrayWithObjects: string1, string2, string3, nil];

buffer = [NSKeyedArchiver archivedDataWithRootObject: myArray1];
myArray2 = [NSKeyedUnarchiver unarchiveObjectWithData: buffer];

tmpStr = [myArray1 objectAtIndex: 0];

[tmpStr setString: @"Yellow"];

NSLog (@"First element of myArray1 = %@", [myArray1 objectAtIndex: 0]);
NSLog (@"First element of myArray2 = %@", [myArray2 objectAtIndex: 0]);