NSDictionary转NSData，代码如下：
+(NSData*)returnDataWith:(NSDictionary*)dict
{
NSData *data = [NSJSONSerialization dataWithJSONObject:dict options:NSJSONWritingPrettyPrinted error:nil]; return data;
}
NSData转NSDictionary，代码如下：
+(NSDictionary*)returnDictionaryWithDataPath:(NSData*)data
{
NSString *receiveStr = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]; NSData * datas = [receiveStr dataUsingEncoding:NSUTF8StringEncoding]; NSDictionary *jsonDict = [NSJSONSerialization JSONObjectWithData:datas options:NSJSONReadingMutableLeaves error:nil]; return jsonDict;
}
NSData转NSString，代码如下：
NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSString转NSData，代码如下：
NSData *data = [@"test" dataUsingEncoding:NSUTF8StringEncoding];
仅做记录！