JSONSerialization Invalid type in JSON write (_SwiftValue)

Question

Why does the following code give me the error:

Invalid type in JSON write (_SwiftValue).

The error is thrown on this line:

Answer 1

You should convert NSObject to NSDictionary at first

Try this to convert to NSDictionary.

#import 

//Add this utility method in your class.
+ (NSDictionary *)dictionaryWithPropertiesOfObject:(id)obj {
    NSMutableDictionary *dict = [NSMutableDictionary dictionary];

    unsigned count;
    objc_property_t *properties = class_copyPropertyList([obj class], &count);

    for (int i = 0; i < count; i++) {
        NSString *key = [NSString stringWithUTF8String:property_getName(properties[i])];
        [dict setObject:[obj valueForKey:key] ? [obj valueForKey:key] : @"" forKey:key];
    }

    free(properties);

    return [NSDictionary dictionaryWithDictionary:dict];
}

Then call this:

NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dic options:0 error:&err];
NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];