I didin't find any MapQuest SDK for iOS developing like the Android one, should i use the javascript with the Safari browser instead?
As far as I know, the JavaScript API doesn't support being embedded into an iOS application, but a browser-based site should work, so you can give it a try! I don't have an exact date, but I do know that MapQuest is releasing an iOS SDK soon.
Another option, if you need an iOS application right now, is to use the MapQuest Mobile Flash Maps API with the latest version of Adobe Flash Builder, which can be used to create applications for iOS, Android, and BlackBerry. There are more details in the MapQuest Devblog.