swift3 - How to migrate array.withUnsafeMutableBufferPointer from swift 2 to swift 3? -

i want use code this link in swif 2

public protocol sglimagetype {     typealias element     var width:int {get}     var height:int {get}     var channels:int {get}     var rowsize:int {get}      func withunsafemutablebufferpointer(         @noescape body: (unsafemutablebufferpointer<element>) throws -> void     ) rethrows } 

a class implemented above protocol:

final public class sglimagergba8 : sglimagetype { ... public func withunsafemutablebufferpointer(@noescape body: (unsafemutablebufferpointer<uint8>) throws -> void) rethrows {     try array.withunsafemutablebufferpointer(){         // unsafe reinterpret cast. careful here.         let st = unsafemutablepointer<uint8>($0.baseaddress)         try body(unsafemutablebufferpointer<uint8>(start: st, count: $0.count*channels))     } } 

in swift 3, line let st = unsafemutablepointer<uint8>($0.baseaddress) throws error:

'init' unavailable: use 'withmemoryrebound(to:capacity:_)' temporarily view memory layout-compatible type

how resolve error?

you convert unsafemutablebufferpointer<uint8> unsafemutablerawbufferpointer, bind uint8 , create unsafemutablebufferpointer<uint8> (using dummy values here properties):

final public class sglimagergba8 : sglimagetype {     public var width: int = 640     public var height: int = 480     public var channels: int = 4     public var rowsize: int = 80     public var array:[(r:uint8,g:uint8,b:uint8,a:uint8)] =         [(r:uint8(1), g:uint8(2), b:uint8(3), a:uint8(4))]      public func withunsafemutablebufferpointer(body: @escaping (unsafemutablebufferpointer<uint8>) throws -> void) rethrows {         try array.withunsafemutablebufferpointer(){ bp in             let rbp = unsafemutablerawbufferpointer(bp)             let p = rbp.baseaddress!.bindmemory(to: uint8.self, capacity: rbp.count)             try body(unsafemutablebufferpointer(start: p, count: rbp.count))         }     } }  sglimagergba8().withunsafemutablebufferpointer { (p: unsafemutablebufferpointer<uint8>) in     print(p, p.count)     p.foreach { print($0) } } 

prints

unsafemutablebufferpointer(start: 0x000000010300e100, count: 4) 4 1, 2, 3, 4 

see unsaferawpointer migration , se-0107 more information.