斯威夫特4:

let x:Int = 45
let str:String = String(describing: x)

开发者。Apple.com >字符集init(describing:)

String(description:)初始化式是将任何类型的实例转换为字符串的首选方法。

自定义字符串转换

let a =123456888
var str = String(a)

OR

var str = a as! String

我更喜欢使用字符串插值

let x = 45
let string = "\(x)"

每个对象都有一些字符串表示。这样事情就简单多了。例如，如果您需要创建具有多个值的字符串。你也可以在里面做任何数学运算或者使用一些条件

let text = "\(count) \(count > 1 ? "items" : "item") in the cart. Sum: $\(sum + shippingPrice)"

弦乐演奏

稍微讲讲性能 UI测试包在iPhone 7(真实设备)与iOS 14

let i = 0
lt result1 = String(i) //0.56s 5890kB
lt result2 = "\(i)" //0.624s 5900kB
lt result3 = i.description //0.758s 5890kB

import XCTest

class ConvertIntToStringTests: XCTestCase {
    let count = 1_000_000
    
    func measureFunction(_ block: () -> Void) {
        let metrics: [XCTMetric] = [
            XCTClockMetric(),
            XCTMemoryMetric()
        ]
        let measureOptions = XCTMeasureOptions.default
        measureOptions.iterationCount = 5
        
        measure(metrics: metrics, options: measureOptions) {
            block()
        }
    }

    func testIntToStringConstructor() {
        var result = ""
        measureFunction {
            for i in 0...count {
                result += String(i)
            }
        }
    }
    
    func testIntToStringInterpolation() {
        var result = ""
        measureFunction {
            for i in 0...count {
                result += "\(i)"
            }
        }
    }
    
    func testIntToStringDescription() {
        var result = ""
        measureFunction {
            for i in 0...count {
                result += i.description
            }
        }
    }
}

斯威夫特2:

var num1 = 4
var numString = "56"
var sum2 = String(num1) + numString
var sum3 = Int(numString)

将Int转换为字符串:

let x : Int = 42
var myString = String(x)

而反过来-将String转换为Int:

let myString : String = "42"
let x: Int? = myString.toInt()

if (x != nil) {
    // Successfully converted String to Int
}

如果你使用的是Swift 2或Swift 3:

let x: Int? = Int(myString)