How to create a string with format?

问题:

I need to create a string with format which can convert int, long, double etc. types into string. Using Obj-C, I can do it via below way.

NSString *str = [NSString stringWithFormat:@"%d , %f, %ld, %@", INT_VALUE, FLOAT_VALUE, DOUBLE_VALUE, STRING_VALUE];

How to do same with swift?

回答1:

I think this could help you:

let timeNow = time(nil)
let aStr = String(format: "%@%x", "timeNow in hex: ", timeNow)
print(aStr)

回答2:

nothing special

let str = NSString(format:"%d , %f, %ld, %@", INT_VALUE, FLOAT_VALUE, LONG_VALUE, STRING_VALUE)

回答3:

let str = "\(INT_VALUE), \(FLOAT_VALUE), \(DOUBLE_VALUE), \(STRING_VALUE)"

Update: I wrote this answer before Swift had String(format:) added to it's API. Use the method given by the top answer.

回答4:

No NSString required!

String(format: "Value: %3.2f\tResult: %3.2f", arguments: [2.7, 99.8])

or

String(format:"Value: %3.2f\tResult: %3.2f", 2.7, 99.8)

回答5:

I would argue that both

let str = String(format:"%d, %f, %ld", INT_VALUE, FLOAT_VALUE, DOUBLE_VALUE)

and

let str = "\(INT_VALUE), \(FLOAT_VALUE), \(DOUBLE_VALUE)"

are both acceptable since the user asked about formatting and both cases fit what they are asking for:

I need to create a string with format which can convert int, long, double etc. types into string.

Obviously the former allows finer control over the formatting than the latter, but that does not mean the latter is not an acceptable answer.

回答6:

var str = "\(INT_VALUE) , \(FLOAT_VALUE) , \(DOUBLE_VALUE), \(STRING_VALUE)"

回答7:

First read Official documentation for Swift language.

Answer should be

var str = "\(INT_VALUE) , \(FLOAT_VALUE) , \(DOUBLE_VALUE), \(STRING_VALUE)"
println(str)

Here

1) Any floating point value by default double

EX.
 var myVal = 5.2 // its double by default;

-> If you want to display floating point value then you need to explicitly define such like a

 EX.
     var myVal:Float = 5.2 // now its float value;

This is far more clear.

回答8:

let INT_VALUE=80
let FLOAT_VALUE:Double= 80.9999
let doubleValue=65.0
let DOUBLE_VALUE:Double= 65.56
let STRING_VALUE="Hello"

let str = NSString(format:"%d , %f, %ld, %@", INT_VALUE, FLOAT_VALUE, DOUBLE_VALUE, STRING_VALUE);
 println(str);

回答9:

I know a lot's of time has passed since this publish, but I've fallen in a similar situation and create a simples class to simplify my life.

public struct StringMaskFormatter {

    public var pattern              : String    = ""
    public var replecementChar      : Character = "*"
    public var allowNumbers         : Bool      = true
    public var allowText            : Bool      = false


    public init(pattern:String, replecementChar:Character="*", allowNumbers:Bool=true, allowText:Bool=true)
    {
        self.pattern            = pattern
        self.replecementChar    = replecementChar
        self.allowNumbers       = allowNumbers
        self.allowText          = allowText
    }


    private func prepareString(string:String) -> String {

        var charSet : NSCharacterSet!

        if allowText && allowNumbers {
            charSet = NSCharacterSet.alphanumericCharacterSet().invertedSet
        }
        else if allowText {
            charSet = NSCharacterSet.letterCharacterSet().invertedSet
        }
        else if allowNumbers {
            charSet = NSCharacterSet.decimalDigitCharacterSet().invertedSet
        }

        let result = string.componentsSeparatedByCharactersInSet(charSet)
        return result.joinWithSeparator("")
    }

    public func createFormattedStringFrom(text:String) -> String
    {
        var resultString = ""
        if text.characters.count > 0 && pattern.characters.count > 0
        {

            var finalText   = ""
            var stop        = false
            let tempString  = prepareString(text)

            var formatIndex = pattern.startIndex
            var tempIndex   = tempString.startIndex

            while !stop
            {
                let formattingPatternRange = formatIndex ..< formatIndex.advancedBy(1)

                if pattern.substringWithRange(formattingPatternRange) != String(replecementChar) {
                    finalText = finalText.stringByAppendingString(pattern.substringWithRange(formattingPatternRange))
                }
                else if tempString.characters.count > 0 {
                    let pureStringRange = tempIndex ..< tempIndex.advancedBy(1)
                    finalText = finalText.stringByAppendingString(tempString.substringWithRange(pureStringRange))
                    tempIndex = tempIndex.advancedBy(1)
                }

                formatIndex = formatIndex.advancedBy(1)

                if formatIndex >= pattern.endIndex || tempIndex >= tempString.endIndex {
                    stop = true
                }

                resultString = finalText

            }
        }

        return resultString
    }

}

The follow link send to the complete source code: https://gist.github.com/dedeexe/d9a43894081317e7c418b96d1d081b25

This solution was base on this article: http://vojtastavik.com/2015/03/29/real-time-formatting-in-uitextfield-swift-basics/

回答10:

Use this following code:

    let intVal=56
    let floatval:Double=56.897898
    let doubleValue=89.0
    let explicitDaouble:Double=89.56
    let stringValue:"Hello"

    let stringValue="String:\(stringValue) Integer:\(intVal) Float:\(floatval) Double:\(doubleValue) ExplicitDouble:\(explicitDaouble) "

回答11:

There is a simple solution I learned with "We <3 Swift" if you can't either import Foundation, use round() and/or does not want a String:

var number = 31.726354765
var intNumber = Int(number * 1000.0)
var roundedNumber = Double(intNumber) / 1000.0

result: 31.726

回答12:

Success to try it:

 var letters:NSString = "abcdefghijkl"
        var strRendom = NSMutableString.stringWithCapacity(strlength)
        for var i=0; i<strlength; i++ {
            let rndString = Int(arc4random() % 12)
            //let strlk = NSString(format: <#NSString#>, <#CVarArg[]#>)
            let strlk = NSString(format: "%c", letters.characterAtIndex(rndString))
            strRendom.appendString(String(strlk))
        }