Question

我有浮点值1.96，然后我想显示1.9作为字符串，如果我使用String（格式：＆＃34;％。1f＆＃34;）结果是2.0，我也尝试使用NumberFormatter作为扩展< / p>

    let formatter = NumberFormatter()
    formatter.numberStyle = .decimal
    formatter.maximumFractionDigits = 1
    formatter.minimumFractionDigits = 1

    return formatter.string(for:  self)!

但仍然是结果2.0

有没有最好的方法来达到1.96到1.9？

Answer 1

老把戏：

var yourResult = Double(floor(10*yourDecimalDigit)/10)

// yourResult = 1.9

转换为像这样的字符串

var string = String(yourResult)

Answer 2

您可以使用Double的常规扩展来截断double值。

Swift 4.0

extension Double {
    func truncate(places : Int)-> Double {
        return Double(floor(pow(10.0, Double(places)) * self)/pow(10.0, Double(places)))
    }
}

使用如下所示

let trimedValue = 1.96.truncate(places: 1) // 1.9

Answer 3

也许有方法可以帮助你，但我喜欢自己做

扩展名：

<!doctype html><html lang="en"><head><title>HTTP Status [400] – [Bad Request]</title><style type="text/css">h1 {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:22px;} h2 {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:16px;} h3 {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:14px;} body {font-family:Tahoma,Arial,sans-serif;color:black;background-color:white;} b {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;} p {font-family:Tahoma,Arial,sans-serif;background:white;color:black;font-size:12px;} a {color:black;} a.name {color:black;} .line {height:1px;background-color:#525D76;border:none;}</style></head><body><h1>HTTP Status [400] – [Bad Request]</h1><hr class="line" /><p><b>Type</b> Status Report</p><p><b>Message</b> Captcha description not correct</p><p><b>Description</b> The server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).</p><hr class="line" /><h3>Apache Tomcat/8.5.15</h3></body></html>

使用它：

extension CGFloat{

    var onlyOneDigits : String {
        var str = "\(self)"
        let count = str.count 
        if self >= 1000 && self < 10000{
            str.removeLast(count - 6)
            return str
        }else if self >= 100{
            str.removeLast(count - 5)
            return str
        }else if self >= 10{
            str.removeLast(count - 4)
            return str
        }else{
            str.removeLast(count - 3)
            return str
        }
    }
}

基本的iOS Decimal Trim

3 个答案: