ios的对象数组生成jsonarray

//1. 初始化可变字符串，存放最终生成json字串
NSMutableString *jsonString = [[NSMutableString alloc] initWithString:@"{\"actorhalls\":["];

for(ExecplanActosHall *hall in actorhalls){

//2. 遍历数组，取出键值对并按json格式存放
NSString *string;

string  = [NSString stringWithFormat:
@"{\"ownerName\":\"%@\",\"ownerId\":\"%@\",\"channelId\":\"%@\",\"ownerType\":\"%ld\"},",hall.ownerName,hall.ownerId,hall.channelId,(long)hall.ownerType];

[jsonString appendString:string];

}
// 3. 获取末尾逗号所在位置
NSUInteger location = [jsonString length]-1;

NSRange range       = NSMakeRange(location, 1);

// 4. 将末尾逗号换成结束的]}
[jsonString replaceCharactersInRange:range withString:@"]}"];

NSLog(@"jsonString = %@",jsonString);

//字典转Json
- (NSString*)dictionaryToJson:(NSDictionary *)dic
{
NSError *parseError = nil;
NSData  *jsonData = [NSJSONSerialization dataWithJSONObject:dic options:NSJSONWritingPrettyPrinted error:&parseError];
return [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
}