应用程序中的MySql数据库导入错误

我突然出现以下错误。我的应用程序尚未更新，数据库也未更改。我不知道发生了什么事。
这是我在日志中得到的错误。我将列出php代码和xcode项目的导入区域。希望有人能知道可能发生了什么。

-JSONValue failed. Error trace is: (
"Error Domain=org.brautaset.JSON.ErrorDomain Code=3 '"Unrecognised leading character'"     UserInfo=0x911e5c0 {NSLocalizedDescription=Unrecognised leading character}"
)

//php code
<?php
$link = mysql_connect('localhost', ‘username', ‘pass');
if (!$link) {
die('Could not connect: ' . mysql_error());
}
mysql_select_db("thedb");
$action = $_GET['action'];
if(!empty($action)) {
if($action == 'listquote') {
    $result = mysql_query("SELECT * FROM quote ORDER BY id DESC");
    $rows = array();
    while($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
        if($row)
            $rows[] = $row;
    }
    echo json_encode($rows);
}
}

mysql_close($link);
?>

DataImportOperation
- (NSError *)processData:(NSData *)content{
NSString *result = [[NSString alloc] initWithData:content   encoding:NSUTF8StringEncoding];
NSArray *arrayList = [result JSONValue];
[result release];
result = nil;
NSString *filePath =  [CWAppSettings pathDicData];
//NSMutableDictionary *dictWrite  = [[NSMutableDictionary alloc] initWithContentsOfFile:filePath];
NSMutableDictionary *dictWrite  = [[NSMutableDictionary alloc] init];
NSMutableArray *plistArray = [[NSMutableArray alloc] init];
NSArray *allValues = [dictWrite objectForKey:@"Quotes"];
if ([allValues count] > 0) {
    for (NSArray *temp in allValues) {
        [plistArray addObject:temp];
    }
}
NSAutoreleasePool *aPool = [[NSAutoreleasePool alloc] init];
long long timestamp = 0;//= [[plistArray objectForKey:@"timestamp"] longLongValue];
for (NSDictionary *dict in arrayList) {
    if ([dict objectForKey:@"quote"] != nil) {
        NSString *quote = [dict objectForKey:@"quote"];
        if ([[NSString stringWithFormat:@"%@", quote] isEqualToString:@"<null>"]) continue;
        NSString *idQuote = [dict objectForKey:@"id"];
        NSArray *array = [NSArray arrayWithObjects:idQuote,quote, nil];
        [plistArray addObject:array];
        DLog(@"%@", quote);
    }
}
[dictWrite setValue:plistArray forKey:@"Quotes"];
[dictWrite writeToFile:filePath atomically:YES];
if (timestamp != 0) {
    [CWAppSettings setLastUpdate:timestamp]; 
}
if (self.delegate && [self.delegate respondsToSelector:@selector(retrieveListOperationDidFinishImportingData)]) {
    [self.delegate retrieveListOperationDidFinishImportingData];
}
if (dictWrite != nil) {
    [dictWrite release];
    dictWrite = nil;
}
if (plistArray != nil) {
    [plistArray release];
    plistArray = nil;
}
if (aPool != nil){
    [aPool release];
    aPool = nil;
}
return nil;

}

就像我说的。。。这很奇怪，因为它突然停止工作了。我不确定可能发生了什么变化。内容仍在数据库中。