自斯威夫特2

Question

我嘗試寫這樣的代碼在SWIFT 2：

//: Playground - noun: a place where people can play 

import Foundation 

struct Point { 

var x: Double 
var y: Double 
} 

func distanceTo (#point: Point) -> Double { 

let a = abs(self.x - point.x) 
let b = abs(self.y - point.y) 

let c = sqrt(a * a + b * b) 

return c 
} 


let pointA = Point(x: 1.0, y: 2.0) 
let pointB = Point(x: 4.0, y: 6.0) 
let distance = pointA.distanceTo (point: pointB) 

，但我得到這個錯誤：

#has been remove from swift, so i change the code to 

func distanceTo (#point: Point) -> Double 

但後來我得到了另一個錯誤：

use of unresolved identifier 'self' 

任何線索如何解決這個錯誤在swift 2？

感謝名單

Answer 1

你需要讓distanceTo爲您點的成員結構 - 看到：

import Foundation 

struct Point { 

    var x: Double 
    var y: Double 

    func distanceTo (point point: Point) -> Double { 

    let a = abs(self.x - point.x) 
    let b = abs(self.y - point.y) 

    let c = sqrt(a * a + b * b) 

    return c 
    } 
} 




let pointA = Point(x: 1.0, y: 2.0) 
let pointB = Point(x: 4.0, y: 6.0) 
let distance = pointA.distanceTo (point: pointB) 

Answer 2

我想你打算做distanceTo的Point成員，所以你必須把它裏面定義爲struct。否則，它將不知道什麼self是指：

struct Point { 
    var x: Double 
    var y: Double 

    func distanceTo (point point: Point) -> Double { 

     let a = abs(self.x - point.x) 
     let b = abs(self.y - point.y) 

     let c = sqrt(a * a + b * b) 

     return c 
    } 
} 

let pointA = Point(x: 1.0, y: 2.0) 
let pointB = Point(x: 4.0, y: 6.0) 
let distance = pointA.distanceTo (point: pointB) 

順便說一句，而不是要求point:，往往你會合並，在方法名稱：

struct Point { 
    var x: Double 
    var y: Double 

    func distanceToPoint(point: Point) -> Double { 

     let a = abs(self.x - point.x) 
     let b = abs(self.y - point.y) 

     let c = sqrt(a * a + b * b) 

     return c 
    } 
} 

let pointA = Point(x: 1.0, y: 2.0) 
let pointB = Point(x: 4.0, y: 6.0) 
let distance = pointA.distanceToPoint(pointB)