iOS NSJSON返回Null [英] iOS NSJSON Returning Null

问题描述

我有以下代码

 hostStr = [hostStr stringByAppendingString:post];
NSData *dataURL =  [NSData dataWithContentsOfURL: [ NSURL URLWithString: hostStr ]];    
NSString *serverOutput = [[NSString alloc] initWithData:dataURL encoding: NSASCIIStringEncoding];    

NSError *error = nil;
NSDictionary *result = [NSJSONSerialization 
                        JSONObjectWithData:dataURL
                        options:kNilOptions 
                        error:&error];

NSArray *files = [result objectForKey:@"GV_Return"];

NSLog(@"Files: %@", files);

// For Each Key we seperate the data and add it to an object to be used.
for (NSDictionary *file in files)
{           
NSString *userNumber = [result objectForKey:@"UserNumber"];
NSLog(@"output: %@", userNumber);
}

我遇到的问题是 NSLog(@"Files:％@"，files); 返回我期望的结果

The problem I'm having is that NSLog(@"Files: %@", files); returns what I expect

Files: (
    {
    UserNumber = 1;
}
)

但是 NSLog(@"output:％@"，userNumber); 返回 NULL

我需要帮助弄清楚为什么NSString * userNumber = [result objectForKey:@"UserNumber"];似乎不应该返回"1".

I need help figuring out why NSString *userNumber = [result objectForKey:@"UserNumber"]; does not seem to be returning "1" as it should.

推荐答案

将代码更改为:

for (NSDictionary *file in files)
{           
NSString *userNumber = [file objectForKey:@"UserNumber"];
NSLog(@"output: %@", userNumber);
}

即 file objectForKey ... ，而不是 result objectForKey ... .您要遍历 files 数组，出于for循环内代码的目的，将其中的每个条目标识为 file .

i.e. file objectForKey..., not result objectForKey.... You're iterating through the files array with each entry in it being identified as file for the purposes of the code within the for loop.

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