Xcode：将NSString从一个类传递到另一个问题 [英] Xcode: Pass NSString from one class to another problem

问题描述

好吧，这应该很容易，但是我仍然会在这里伤脑筋：

OK this should be an easy one but still im breaking my head here:

在我的根视图控制器中，我有一个 NSString 称为 entry，并且运行良好。我 NSLogged 它可以工作。
我有另一个名为 ParseOperation的类，其中有一个名为 localEntry的 NSString ，我试图将变量 entry发送给 ParseOperation来自 RootViewController，这是我的RootViewController代码：

In my root view controller I have a NSString called "entry" and is working perfectly. I NSLogged it and it works. I have another class called ´ParseOperation´ and in it i have a NSStringcalled "localEntry" and im trying to send to "ParseOperation" the variable "entry" from "RootViewController" this is my RootViewController code for that:

RootViewController.m  

ParseOperation *parseOperation = [[ParseOperation alloc] init];  
parseOperation.localEntry = entry;

它只是不起作用。如果我在ParseOperation.m中 NSLog ，它将返回 null，但是如果我在RootViewController上执行它，它将返回正确的变量。是的，我确实导入了ParseOperation.h

It just doesn't work. If I NSLog in my ParseOperation.m it returns "null", but if i do it on my RootViewController it returns the correct variable. and yes i did imported the ParseOperation.h

这里是ParseOperation代码（仅使用localEntry的部分）：

Here is the ParseOperation code (only the part that uses localEntry):

ParseOperation.h  

@interface ParseOperation : NSOperation <NSXMLParserDelegate>
{
    NSString        *localEntry;
}
@property (nonatomic, retain) NSString *localEntry;

@end

ParseOperation.m  

@synthesize localEntry;

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

    //NSLog(@"entrada %@",localEntry);
    if ([elementName isEqualToString:localEntry])
    {
        self.workingEntry = [[[AppRecord alloc] init] autorelease];
    }
    storingCharacterData = [elementsToParse containsObject:elementName];
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName
                                  namespaceURI:(NSString *)namespaceURI
                                 qualifiedName:(NSString *)qName
{
    if (self.workingEntry)
    {
        if (storingCharacterData)
        {
            NSString *trimmedString = [workingPropertyString     stringByTrimmingCharactersInSet:
                                   [NSCharacterSet whitespaceAndNewlineCharacterSet]];
            [workingPropertyString setString:@""];  // clear the string for next time
            if ([elementName isEqualToString:kIDStr])
            {
                self.workingEntry.appURLString = trimmedString;
            }
            else if ([elementName isEqualToString:kNameStr])
            {        
                self.workingEntry.appName = trimmedString;
            }
            else if ([elementName isEqualToString:kImageStr])
            {
                self.workingEntry.imageURLString = trimmedString;
            }
            else if ([elementName isEqualToString:kArtistStr])
            {
                self.workingEntry.artist = trimmedString;
            }
        }
        else if ([elementName isEqualToString:localEntry])
        {
            [self.workingArray addObject:self.workingEntry];  
            self.workingEntry = nil;
        }
    }
}

谢谢！

推荐答案

要回答我自己的问题，我只需要通过将以下内容添加到parseOperation的标头中，以编程方式连接viewController和ParseOperation：

To answer my own question I just had to connect the viewController and the ParseOperation programmatically by adding the following to my header in the parseOperation:

@class RootViewController;

RootViewController *rootViewController;

@property (nonatomic, retain) IBOutlet RootViewController *rootViewController;

以下是ParseOperation的m文件：

And the following on the m file of the ParseOperation:

#import "RootViewController.h"

rootViewController = [[RootViewController alloc]init];

在解析操作之后，我刚刚声明：

After that in the parse operation I just declared:

localEntry= rootViewContoller.entry;

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