copy one NSString to another - iphone

Question

How to copy one NSString to another?
#interface MyData : NSObject
{
#private
//user's private info
NSInteger uID;
NSString *name;
NSString *surname;
NSString *email;
NSString *telephone;
//user's picture
UIImage *image;
}
#property (nonatomic, assign) int uID;
#property (nonatomic, retain) NSString *name;
#property (nonatomic, retain) NSString *surname;
#property (nonatomic, retain) NSString *email;
#property (nonatomic, retain) NSString *telephone;
#property (nonatomic, retain) UIImage *image;
#end
I have two objects of this type. MyData *obj1, obj2;
First is initialized. Second I want to initialize with first.
obj2 = [obj1 copy]; //crashes
newData.surname = data.surname; //crashes to
newData.email = data.email;
newData.telephone = data.telephone;
I neeeeed a COPY of second object NOT RETAIN!!! Help please! Thanx!

Answer 1

you can use the NSString method stringWithString.
See also stringwithstring, what's the point? to understand when this might be preferred to simply giving it the same string.

Answer 2

your object should probably implement the copy itself:
#implementation MyData
-(id)copyWithZone:(NSZone *)zone
{
MyData *obj = [[[self class] alloc] init];
obj.uID = self.uId;
obj.name = self.name
...
return obj;
}
....
#end

Answer 3

Change your #property's to use copy instead of retain:
#property (nonatomic) int uID;
#property (nonatomic, copy) NSString *name;
#property (nonatomic, copy) NSString *surname;
#property (nonatomic, copy) NSString *email;
#property (nonatomic, copy) NSString *telephone;
#property (nonatomic, copy) UIImage *image;
Note that you also don't need the assign for the uID. Just leave that part out. Then you can easily create a copy by alloc and init-ing a second MyData object and assigning the properties :
MyData data = [[MyData alloc] init];
newData.surname = data.surname;
newData.email = data.email;
newData.telephone = data.telephone;