i want to develop an application that is capable of using 2G 3G or 4G depending upon the availability of the network. Because this app will be used in different countries and there is a support of only 2G in some countries while some support 3G or 4G.. i am a little bit confused whether my app will automatically use the Fastest network available or i will have to explicitly code for each one.
According to Apple's documentation, WiFi is what is chosen first. If that fails, then it goes to the next available (and presumably fastest) cellular network data connection.
This is the kind of thing programmers do not have to worry about when designing apps for iOS.