1.?NSDictionary->JSON

NSDictionary *jsonDic = @{};

NSData *jsonData = [NSJSONSerialization dataWithJSONObject:jsonDic options:0 error:nil]; // 如果不想要 JSON 字符串里帶空格或換行等 options 傳 0

NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

2.?JSON->NSDictionary

NSString *jsonString = @"";

NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];

NSDictionary *jsonDic = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:nil];

3.?NSJSONReadingOptions 枚舉說明

NSJSONReadingMutableContainers //?Specifies that arrays and dictionaries are created as mutable objects.

NSJSONReadingMutableLeaves //?Specifies that leaf strings in the JSON object graph are created as instances of NSMutableString.

NSJSONReadingAllowFragments //?Specifies that the parser should allow top-level objects that are not an instance of NSArray or NSDictionary.