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将一个NSString复制到另一个NSString

copywithzone copy nsstring iphone

1

yozhik · 技术社区 · 15 年前

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

我有两件这种类型的东西。MyData*obj1,obj2;

第一个已初始化。第二个我想用第一个初始化。

obj2 = [obj1 copy];   //crashes

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

我需要第二个对象的副本不保留!!! 救命啊!谢谢!

3 回复 | 直到 15 年前

1

4

Romain 15 年前

您的对象可能应该实现副本本身:

@implementation MyData

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

....
@end

2

5

Community Mohan Dere 9 年前

可以使用NSString方法 stringWithString .

见 also stringwithstring, what's the point? 了解什么时候可能更倾向于给它相同的字符串。

3

2

Ken Pespisa 15 年前

将@property更改为使用copy而不是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;

注意,您也不需要分配uID。把那部分去掉。然后,您可以通过分配和初始化第二个MyData对象并分配属性来轻松创建副本:

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