Playing around with Swift pointers

Pointers.swift

import Foundation

struct P {
    var b: Bool
    var i: Int
}

MemoryLayout<P>.size       // returns 9
MemoryLayout<P>.alignment  // returns 8
MemoryLayout<P>.stride     // returns 16

// Arrays
var array = [1,2, 3, 4, 5]
var array2 = [6, 7, 8, 9, 10]
var integer = 1
array.withUnsafeMutableBufferPointer { (buffer) -> Void in
    array2.withUnsafeMutableBufferPointer({ (buffer2) -> Void in
        buffer.baseAddress?.moveAssign(from: buffer2.baseAddress!, count: 3)
    })
}

print(array)
print(array2)

// Raw Pointers
let pointer = UnsafeMutableRawPointer.allocate(byteCount: MemoryLayout<Int>.size, alignment: MemoryLayout<Int>.alignment)

pointer.storeBytes(of: 5, as: Int.self)
(pointer + MemoryLayout<Int>.stride).storeBytes(of: 6, as: Int.self)

let buff = UnsafeBufferPointer(start: pointer.assumingMemoryBound(to: Int.self), count: 2)

let s = buff.map({ $0 })

print(s)
buff.deallocate()


// Generic Pointers
let p = UnsafeMutablePointer<Int>.allocate(capacity: 4)
p.initialize(to: 4)
p.advanced(by: 1).initialize(to: 3)
var b = UnsafeBufferPointer<Int>(start: p, count: 4)
print(b.map({ $0 }))

p.deinitialize(count: 4)
p.deallocate()

let i = UnsafeMutablePointer<NSMutableString>.allocate(capacity: 2)
i.initialize(repeating: NSMutableString(), count: 2)
i.pointee.append("hue")
i.advanced(by: 1).pointee = NSMutableString(extendedGraphemeClusterLiteral: "dlsakj")
var strs = UnsafeBufferPointer<NSMutableString>(start: i, count: 2)
print(strs.map({ $0 }))
i.deinitialize(count: 2)
strs.deallocate()

// Bytes manipulation
var ps = P(b: true, i: 10)

withUnsafeMutableBytes(of: &ps) { (pointer) in
    pointer.swapAt(0, 1)
}

print(ps.i)

let i8: UInt8 = 0
print(~i8)