8.改进应用程序

##8.1数字格式设置（storyboard） ##8.1.2可选类型拆封

import Cocoa
extension Double{
	var dollars : String{
		let formatter : NumberFormatter = NumberFormatter()//NSNumberFormatter弃用
		var result : String?//将result的类型声明为可选类型
		formatter.numberStyle = .currency
		result = formatter.string(from: NSNumber(value:self))
//		.string(from: NSNumber)返回为可选类型，由于若是转换失败会返回nil
		if (result == nil){
			return "FORMAT FAILURE!"
		}
		return result!//拆封可选变量，拆封指的是将变量转换为值不能为nil的变量
	}

}
class ViewController: NSViewController {
	//"!"为隐式封拆的可选类型，至关于告诉编译器，在该变量为nil时毫不会访问它
	@IBOutlet weak var loanAmountField :NSTextField!
	@IBOutlet weak var interestRateField : NSTextField!
	@IBOutlet weak var yearsField : NSTextField!
	@IBOutlet weak var resultsField : NSTextField!
	var simpleInterestCalculator : SimpInterest = SimpInterest()
	var compoundInterestCalculator : CompoundInterest = CompoundInterest()
	override func viewDidLoad() {
		super.viewDidLoad()

	}

	override var representedObject: Any? {
		didSet {
		
		}
	}
	[@IBAction](https://my.oschina.net/u/866341) func buttonClicked(sender : NSButton){
		var result : Double
		result = simpleInterestCalculator.calculate(loanAmount: loanAmountField.doubleValue, interestRate: interestRateField.doubleValue , years: yearsField.integerValue)
//		self.resultsField.stringValue = result.description//description让类可以返回其数据的String表示
		self.resultsField.stringValue = result.dollars
	}
	@IBAction func compoundbuttonClicked(_ sender: NSButton) {
		var result : Double
		result = compoundInterestCalculator.calculate(loanAmount: loanAmountField.doubleValue, interestRate: interestRateField.doubleValue , years: yearsField.integerValue)
		//		self.resultsField.stringValue = result.description//description让类可以返回其数据的String表示
		self.resultsField.stringValue = result.dollars
	}
}

8.2单元测试 if Use of undeclared type 'SimpInterest' take class Target Membership choose

import XCTest

class MACSwiftTeststwo: XCTestCase {
	var mySimpInterestCalculator : SimpInterest = SimpInterest()
	var myCompoundInterestCalculator : CompoundInterest = CompoundInterest()
	
    override func setUp() {
        super.setUp()
        // Put setup code here. This method is called before the invocation of each test method in the class.
		//在这里插入设置代码，调用这个类中的每一个测试方法前，都将调用这个方法
    }
    
    override func tearDown() {
        // Put teardown code here. This method is called after the invocation of each test method in the class.
		//在这里插入清理代码，调用这个类中的每一个测试方法后，都将调用这个方法
        super.tearDown()
    }
	//功能测试用例
	func testSimpleInterest(){
		var result : Double
		result = mySimpInterestCalculator.calculate(loanAmount: 25_000, interestRate: 0.08, years: 10)
		XCTAssertEqualWithAccuracy(result,45000,accuracy:0.1 ,"Unexpected result \(result)")//1.要评估的变量 2.该变量应包含的值 3准确因子 4.未经过测试时显示的String
		//传入的变量和预期结果相差不超过0.1
	}
	func testCompoundInterest(){
		var result : Double
		result = myCompoundInterestCalculator.calculate(loanAmount: 25_000, interestRate: 0.08, years: 10)
		XCTAssertEqualWithAccuracy(result, 25002+0.1, accuracy: 0.1,"Unexpected result \(result)")
	
	}
    //示例测试方法
//    func testExample() {
//        // This is an example of a functional test case.
//        // Use XCTAssert and related functions to verify your tests produce the correct results.
//    }
//    
//    func testPerformanceExample() {
//        // This is an example of a performance test case.
//        self.measure {
//            // Put the code you want to measure the time of here.
//        }
//    }
	
}