Question

我只是从IOS开始并为我的计算机科学类创建一个IOS应用程序（最终项目），它使用JSON从远程MySql数据库获取数据。

这是我从ViewDidLoad调用的方法：

- (void)loadJSON
{
//-- Make URL request with server
NSHTTPURLResponse *response = nil;
NSString *jsonUrlString = [NSString stringWithFormat:@"http://vito-service.ru/studentsconnect/profile.php"];
NSURL *url = [NSURL URLWithString:[jsonUrlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

//-- Get request and response though URL
NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url];
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:nil];

//-- JSON Parsing
NSMutableArray *result = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableContainers error:nil];
NSLog(@"Result = %@",result);

}

和NSLog打印正确的数据：

Result = {
users =     (
            {
        IdUser = 1;
        facebook = "";
        fullname = "";
        instagram = "";
        phonenumber = "";
        username = moderas;
    },
            {
        IdUser = 2;
        facebook = "fb.com/petroffmichael";
        fullname = "Michael Perov";
        instagram = "@petroffmichael";
        phonenumber = "(650)557-6168";
        username = petroffmichael;
    },
            {
        IdUser = 3;
        facebook = "fb.com/testuser";
        fullname = "Test User";
        instagram = "@testuser";
        phonenumber = "111 111-1111";
        username = testuser;
    }
);
}

但是如何将这些数据作为字符串检索以将它们放到标签上呢？我尝试了很多不同的创建数据对象的选项，我在这里找到堆栈溢出但是我总是得到一个＆＃34;无法识别的选择器发送到实例＆＃34;错误。我也试过创建一个单独的NSObject

@synthesize IdUser, username, fullname, phonenumber, facebook, instagram;

- (id) initWithUsername: (NSString *)uUsername andUserFullName: (NSString *)uFullname andUserPhonenumber: (NSString *)uPhonenumber andUserFacebook: (NSString *)uFacebook andUserInstagram: (NSString *)uInstagram andUserId: (NSString *)uId
{
self = [super init];
if (self) {
    username = uUsername;
    fullname = uFullname;
    phonenumber = uPhonenumber;
    facebook = uFacebook;
    instagram = uInstagram;
    IdUser = uId;
}

return self;
}

然后使用此方法检索数据：

-(void)retrieveData
{
NSURL *url = [NSURL URLWithString:getDataUrl];
NSData *data = [NSData dataWithContentsOfURL:url];

jsonArray = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];

usersArray = [[NSMutableArray alloc] init];

for (int i=0; i<jsonArray.count; i++) {
    NSString * uId = [[jsonArray objectAtIndex: i] objectForKey:@"IdUser"];
    NSString * uUsername = [[jsonArray objectAtIndex: i] objectForKey:@"username"];
    NSString * uFullname = [[jsonArray objectAtIndex: i] objectForKey:@"fullname"];
    NSString * uPhonenumber = [[jsonArray objectAtIndex: i] objectForKey:@"phonenumber"];
    NSString * uFacebook = [[jsonArray objectAtIndex: i] objectForKey:@"facebook"];
    NSString * uInstagram = [[jsonArray objectAtIndex: i] objectForKey:@"instagram"];

    [usersArray addObject:[[User alloc] initWithUsername:uUsername andUserFullName:uFullname andUserPhonenumber:uPhonenumber andUserFacebook:uFacebook andUserInstagram:uInstagram andUserId:uId]];
}

}

我有所有重要的#import＆＃39;但我仍然会遇到同样的错误：

2014-04-23 18:35:26.612 testimage[47155:70b] -[__NSCFDictionary objectAtIndex:]:     unrecognized selector sent to instance 0xa72a8b0
2014-04-23 18:35:26.813 testimage[47155:70b] *** Terminating app due to uncaught  exception 'NSInvalidArgumentException', reason: '-[__NSCFDictionary objectAtIndex:]:     unrecognized selector sent to instance 0xa72a8b0'

有人可以帮忙找到合适的解决方案吗？谢谢！

在收听多条评论后，我更改了代码，但仍然收到错误..

我想我还在做错事

jsonArray不再是一个数组了：

@property (nonatomic, strong) NSDictionary *jsonArray;
@property (nonatomic, strong) NSMutableArray *usersArray;

然后方法：

-(void)retrieveData
{
NSURL *url = [NSURL URLWithString:getDataUrl];
NSData *data = [NSData dataWithContentsOfURL:url];

jsonArray = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
usersArray = [[NSMutableArray alloc] init];

for (NSDictionary *dict in jsonArray)
{
    NSString * uId = [dict objectForKey:@"IdUser"];
    NSString * uUsername = [dict objectForKey:@"username"];
    NSString * uFullname = [dict objectForKey:@"fullname"];
    NSString * uPhonenumber = [dict objectForKey:@"phonenumber"];
    NSString * uFacebook = [dict objectForKey:@"facebook"];
    NSString * uInstagram = [dict objectForKey:@"instagram"];

    [usersArray addObject:[[User alloc] initWithUsername:uUsername andUserFullName:uFullname andUserPhonenumber:uPhonenumber andUserFacebook:uFacebook andUserInstagram:uInstagram andUserId:uId]];
}

}

我仍然遇到同样的错误：

2014-04-23 20:44:43.971 testimage[48285:70b] -[__NSCFString objectForKey:]:  unrecognized selector sent to instance 0xa5547d0
2014-04-23 20:44:44.053 testimage[48285:70b] *** Terminating app due to uncaught  exception 'NSInvalidArgumentException', reason: '-[__NSCFString objectForKey:]:   unrecognized selector sent to instance 0xa5547d0'

Answer 1

仔细观察那个输出。它不是你所说的。你所拥有的不是一个数组 - 它是一个带有一个键@"users"的字典，其值是一个数组。这是它在以{ users = …开头时告诉你的内容。如果你想要数组，你需要从字典中检索它。

Answer 2

试试这个：

NSDictionary *res = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableContainers error:nil];
NSMutableArray *result = [res objectForKey:@"users"];

这样做。响应不是NSArray。这是一本字典。首先从字典中获取数组，然后在使用时使用它。希望这有助于...：）

修改

您可以通过以下方式重写循环：

for (NSDictionary *dict in jsonArray) { //dict is a NSDictionary. Just get value for keys }

从NSMutableArray中检索数据

在收听多条评论后，我更改了代码，但仍然收到错误..

2 个答案: