[Swift]数组元素是class和struct时的引用测试

结论写在最前面：

数组元素是struct时，复制数组后修改，以及修改指向数组元素的变量都不会影响到原来的数组；元素是class时则会。
详细的测试用例一图清楚明了。

测试结果

测试代码

    class Person : CustomDebugStringConvertible {
        
        var debugDescription: String {
            return "debug:\(age)"
        }
        
        var age : Int = 0
        init(age:Int){
            self.age = age
        }
    }
    
   func forClass() {
        var perArr = [Person]()
        perArr.append(Person(age:12))
        perArr.append(Person(age:13))
        perArr.append(Person(age:14))
        
        print("A:perArr = \(perArr)")
        //perArr = [debug:12, debug:13, debug:14]
        
        var copyArr = perArr
        print("A:copyArr = \(copyArr)")
        //A:copyArr = [debug:12, debug:13, debug:14]
        
        //==============[case 1]=======================
        //操作：对数组复制后，修改复制得到的数组的元素，
        copyArr[1].age = 100
        print("B:copyArr = \(copyArr)")
        //B:copyArr = [debug:12, debug:100, debug:14]
        print("B:perArr = \(perArr)")
        //B:perArr = [debug:12, debug:100, debug:14]
        //结果：原来数组的元素也会发生改变，两个输出结果里都是'debug:100';所以数组元素依然是引用
        
        //==============[case 2]=======================
        //操作：新建一个元素，把元素添加到数组后再修改该元素
        let testP = Person(age:999)
        copyArr.append(testP)
        print("C:copyArr = \(copyArr)")
        //C:copyArr = [debug:12, debug:100, debug:14, debug:999]
        print("A:testP = \(testP)")
        //A:testP = 999
        testP.age = 888
        print("D:copyArr = \(copyArr)")
        //D:copyArr = [debug:12, debug:100, debug:14, debug:888]
        //结果：数组的元素也会发生改变，输出结果里有'debug:888';所以数组元素依然是引用
    }

   struct User : CustomDebugStringConvertible {
        var age : Int = 0
        var debugDescription: String {
            return "debug:\(age)"
        }
    }

    func forStruct() {
        var perArr = [User]()
        perArr.append(User(age:12))
        perArr.append(User(age:13))
        perArr.append(User(age:14))
        
        print("A:perArr = \(perArr)")
        //perArr = [debug:12, debug:13, debug:14]
        
        var copyArr = perArr
        print("A:copyArr = \(copyArr)")
        //A:copyArr = [debug:12, debug:13, debug:14]
        
        //==============[case 1]=======================
        //操作：对数组复制后，修改复制得到的数组的元素，
        copyArr[1].age = 100
        print("B:copyArr = \(copyArr)")
        //B:copyArr = [debug:12, debug:100, debug:14]
        print("B:perArr = \(perArr)")
        //B:perArr = [debug:12, debug:13, debug:14]
        //结果：原来数组的元素不会发生改变，两个输出结果里都是'debug:100'和‘debug:13’
        
        //==============[case 2]=======================
        //操作：新建一个元素，把元素添加到数组后再修改该元素
        var testP = User(age:999)
        copyArr.append(testP)
        print("C:copyArr = \(copyArr)")
        //C:copyArr = [debug:12, debug:100, debug:14, debug:999]
        print("A:testP = \(testP)")
        //A:testP = 999
        testP.age = 888
        print("D:copyArr = \(copyArr)")
        //D:copyArr = [debug:12, debug:100, debug:14, debug:999]
        //结果：数组的元素不会发生改变，输出结果里还是'debug:999';
    }