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This article introduces the relevant knowledge of "how to write the code for iOS to achieve the small functions of calculators". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

In this paper, the calculator app is implemented by ios, and the mvc structure will be used to reconstruct it later.

Import UIKitclass CalculViewController: UIViewController {@ IBOutlet weak var display: UILabel! Var userIsInTheMiddleOFTypingANumber:Bool=false @ IBAction func appendDigit (sender: UIButton) {let digit=sender.currentTitle! If userIsInTheMiddleOFTypingANumber {display.textbooks display.textbooks examples} else {display.text=digit userIsInTheMiddleOFTypingANumber=true}} var operandstack:Array=Array () @ IBAction func operate (sender: UIButton) {let operation=sender.currentTitle! If userIsInTheMiddleOFTypingANumber {enter ()} switch operation {case "×": performeOperation {$0,000,1} case "/": performeOperation {$1Compact / 0} case "+": performeOperation {$0,000,1} case "-": performeOperation {$1Muth0} case "√": performeOperation {sqrt ($0)} default: break} } / / func multiply (op1:Double Op2:Double)-> Double {/ / return op1*op2 / /} func performeOperation (operation: (Double,Double)-> Double) {if operandstack.count > = 2 {displayValue=operation (operandstack.removeLast () Operandstack.removeLast () enter ()}} private func performeOperation (operation:Double- > Double) {if operandstack.count > = 1 {displayValue=operation (operandstack.removeLast ()) enter ()} @ IBAction func enter () {userIsInTheMiddleOFTypingANumber=false operandstack.append (displayValue) print ("operandstack=\ (operandstack)")} var DisplayValue:Double {get {return NSNumberFormatter (). NumberFromString (display.text!)! .flexileValue} set {display.text= "\ (newValue)" userIsInTheMiddleOFTypingANumber=false}} knowledge points are as follows

Setter and getter of Computational attributes

Swift uses a function as a parameter

Overloading of swift. For more information, please see swift override.

The effect is as follows

Add model file

Import Foundationclass CalculatorBrain {private enum Op: CustomStringConvertible {case operand (Double) case UnaryOperation (String,Double- > Double) case BinaryOperation (String, (Double,Double)-> Double) var description:String {get {switch self {case .operand (let operand): return "\ (operand)" case .BinaryOperation (let symbol _): return symbol case .UnaryOperation (let symbol _): return symbol} private var opstack= [Op] () private var knowOps= [String:Op] () init () {func learnOp (op:Op) {knowOps [op.description] = op} learnOp (Op.BinaryOperation ("×") {$0,000.1}) LearnOp (Op.BinaryOperation ("/") {$1 sqrt (0)}) learnOp (Op.BinaryOperation ("+") {$0 / 2}) learnOp (Op.BinaryOperation ("-") {$1 / 2 / 2) learnOp (Op.UnaryOperation ("√") {sqrt ($0)}) / / knowOps ["×"] = Op.BinaryOperation ("×") {$0mm / 1} / knowOps ["/"] = Op.BinaryOperation ("/") / knowOps ["+"] = Op.BinaryOperation ("+") {$0icing 1} / / knowOps ["-"] = Op.BinaryOperation ("-") {$1private func evaluate / / knowOps ["√"] = Op.UnaryOperation ("√") {sqrt ($0)}} private func evaluate (ops: [Op])-> (result:Double? RemainOps: [Op]) {if! ops.isEmpty {var remainOps=ops Let op=remainOps.removeLast () switch op {case Op.operand (let operand): return (operand,remainOps) case Op.UnaryOperation (_, let operation): let operandEvalution=evaluate (remainOps) if let operand=operandEvalution.result {return (operation (operand)) OperandEvalution.remainOps)} case Op.BinaryOperation (_, let operation): let operandEvlution1=evaluate (remainOps) if let operand1=operandEvlution1.result {let operandEvlution2=evaluate (operandEvlution1.remainOps) if let operand2=operandEvlution2.result {return (operation (operand1,operand2) OperandEvlution2.remainOps)} return (nil,ops)} func evaluate ()-> Double? {let (result) Remainder) = evaluate (opstack) print ("\ (opstack) =\ (result) with\ (remainder) left over") return result} func pushOperand (operand:Double)-> Double? {opstack.append (Op.operand (operand)) return evaluate ()} func performOperation (symbol:String)-> Double? {if let operation=knowOps [symbol] {opstack.append (operation)} return evaluate ()}}

Controll is modified to

Import UIKitclass CalculViewController: UIViewController {@ IBOutlet weak var display: UILabel! Var userIsInTheMiddleOFTypingANumber:Bool=false var brain=CalculatorBrain () @ IBAction func appendDigit (sender: UIButton) {let digit=sender.currentTitle! If userIsInTheMiddleOFTypingANumber {display.textbooks display.textbooks examples} else {display.text=digit userIsInTheMiddleOFTypingANumber=true}} / / var operandstack:Array=Array () @ IBAction func operate (sender: UIButton) {if userIsInTheMiddleOFTypingANumber {enter ()} if let operation=sender.currentTitle {if let result=brain.performOperation (operation) { DisplayValue=result} else {displayValue=0}} @ IBAction func enter () {userIsInTheMiddleOFTypingANumber=false if let result=brain.pushOperand (displayValue) {displayValue=result} else {displayValue=0}} var displayValue:Double {get {return NSNumberFormatter (). NumberFromString (display. Text!)! .accounleValue} set {display.text= "\ (newValue)" userIsInTheMiddleOFTypingANumber=false}} "how to write the code for iOS to implement the small function of calculator" is introduced here. Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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