将一个NSString复制到另一个

Question

如何将一个NSString复制到另一个NSString？

@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 

我有这种类型的两个对象。 MyData * obj1，obj2;

首先被初始化。其次，我想先初始化。

obj2 = [obj1 copy]; //crashes 

    newData.surname = data.surname; //crashes to 
    newData.email = data.email; 
    newData.telephone = data.telephone; 

我neeeeed的第二个对象不保留一个COPY！请帮助！感谢名单！

Answer 1

你的对象也许应该实现自身拷贝：

@implementation MyData 

-(id)copyWithZone:(NSZone *)zone 
{ 
    MyData *obj = [[[self class] alloc] init]; 
    obj.uID = self.uId; 
    obj.name = self.name 
    ... 
    return obj; 
} 

.... 
@end 

Answer 2

可以使用的NSString方法stringWithString。

请参阅also stringwithstring, what's the point?了解何时可能会优先考虑简单地给它一个相同的字符串。

Answer 3

更改@财产的使用副本，而不是保留：

@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; 

请注意，您也不必为UID的分配。只要把那部分放开。然后你可以很容易地通过alloc创建一个副本，并启动第二个MyData对象并分配属性：

MyData data = [[MyData alloc] init]; 
newData.surname = data.surname; 
newData.email = data.email; 
newData.telephone = data.telephone;