Is Swift a dynamic or static language?

Question

I'm just curious if Swift is dynamic like php or static, I mean can I generate classes while an application is running?

Answer 1

It is static - very static. The compiler must have all information about all classes and functions at compile time. You can "extend" an existing class (with an extension), but even then you must define completely at compile time what that extension consists of.

Objective-C is dynamic, and since, in real life, you will probably be using Swift in the presence of Cocoa, you can use the Objective-C runtime to inject / swizzle methods in a Swift class that is exposed to Objective-C. You can do this even though you are speaking in the Swift language. But Swift itself is static, and in fact is explicitly designed in order to minimize or eliminate the use of Objective-C-type dynamism.

Answer 2

Swift itself, is statically typed. When used with Cocoa, you get access to the objective-c runtime library which gives you the ability to use dynamic classes, messages and all. This doesn't mean the language itself is dynamically typed. You could do the same with C or any other language that supports a bridge to C by using libobjc.A.dylib.