objective-c - 如何在以下方法中保留值？

Question

@interface SignDocumentController : UIViewController<NSXMLParserDelegate> {
    NSMutableString *signFaxString;
    NSString * messageId;
    NSMutableData *xmlData;
    NSURLConnection *connectionInprogress;
    NSURLConnection *connectionInprogress2;


    NSString * annotationKey;

    NSString *firstName;
    NSString *lastName;
    NSString *date;
    NSString *signature;


    IBOutlet UIImageView *image;
}

@property(nonatomic,retain)UIImageView * image;


@end

-(void)parser:(NSXMLParser *)parser
didStartElement:(NSString *) elementName
 namespaceURI:(NSString *)namespaceURI
qualifiedName:(NSString *)qName
   attributes:(NSDictionary *)attributeDict
{

    if ([elementName isEqual:@"SignatureInfo"]) {

        signFaxString = [[NSMutableString alloc]init]; 

        firstName = [attributeDict objectForKey:@"FirstName"];
        lastName = [attributeDict objectForKey:@"LastName"];
        date = [attributeDict objectForKey:@"Date"];
        signature = [attributeDict objectForKey:@"Signature"];
    }

    if ([elementName isEqual:@"AddAnnotationResult"]) {
        signFaxString = [[NSMutableString alloc]init]; 
    }


}

名字、姓氏、日期、签名的值不会保留，当我尝试以不同的方法访问名字、姓氏等时出现错误:

[CFString respondsToSelector:]: 发送到释放实例 0x4ec63b0 的消息

我试过使用:

firstName = [NSString stringWithString attributeDict objectForKey:@"FirstName"]; 

但这也不起作用。我知道这是一个愚蠢的问题，但我需要一些帮助。

谢谢

Answer 1

您还可以将 firstName 和其他声明为属性并 retain 。如下图

@property(nonatomic,retain)NSString* firstName;
@property(nonatomic,retain)NSString* lastName;    
@property(nonatomic,retain)NSString* date;
@property(nonatomic,retain)NSString* signature;

在 .m 类中。

@synthesize firstName,date,lastName,signature;

并在 dealloc 函数中释放它们。

与 self 一起使用您类中的所有属性变量。

self.firstName = [NSString stringWithString:attributeDict objectForKey:@"FirstName"];

已编辑:

同时考虑 @bbum 评论..