Is it possible to mix C and Swift?

Question

I've studied the basics of Swift and some C. How could I combine C and Swift in one project? Could I ignore Objective-C?

Answer 1

It is very much possible to mix Swift and C. In fact it's pretty easy. For example, if you type import Darwin into a playground, you will find all sorts of C functions:

import Darwin

let i = atoi("42")
let path = String.fromCString(getenv("PATH"))

let voidptr = malloc(10 * UInt(sizeof(Int)))
let ptr = UnsafeMutablePointer<Int>(voidptr)
for i in 0..<10 {
    ptr[i] = i
}
let buffer = UnsafeBufferPointer(start: ptr, count: 10)
reduce(buffer, 0, +) // sum(1 to 10) = 45
free(ptr)

There are various convenience conversions, for example in the above code, "42" was automatically converted to a C-style string to be passed into atoi. Similarly, if you declare var i: Int = 0, you can pass that into a C API that takes a C pointer-to-int as f(&i), and arrays are similarly auto-converted to pointers when you pass them in.

See the docs on the Apple website for more info on how you can interact with C from Swift.