谁能告诉我如何在Swift中舍入一个双数值到x位小数点后数位?
我有:
var totalWorkTimeInHours = (totalWorkTime/60/60)
totalWorkTime是一个NSTimeInterval (double)，单位为秒。
totalWorkTimeInHours会给我小时数，但它给我的时间量是如此长的精确数字，例如1.543240952039......
当我打印totalWorkTimeInHours时，我如何将其四舍五入到1.543 ?
当前回答
//find the distance between two points
let coordinateSource = CLLocation(latitude: 30.7717625, longitude:76.5741449 )
let coordinateDestination = CLLocation(latitude: 29.9810859, longitude: 76.5663599)
let distanceInMeters = coordinateSource.distance(from: coordinateDestination)
let valueInKms = distanceInMeters/1000
let preciseValueUptoThreeDigit = Double(round(1000*valueInKms)/1000)
self.lblTotalDistance.text = "Distance is : \(preciseValueUptoThreeDigit) kms"
其他回答
如果你想在逗号后面只有0表示圆，试试这个:
extension Double {
func isInteger() -> Any {
let check = floor(self) == self
if check {
return Int(self)
} else {
return self
}
}
}
let toInt: Double = 10.0
let stillDouble: Double = 9.12
print(toInt.isInteger) // 10
print(stillDouble.isInteger) // 9.12
在Swift 5.5和Xcode 13.2中:
let pi: Double = 3.14159265358979
String(format:"%.2f", pi)
例子:
附注:自Swift 2.0和Xcode 7.2以来一直如此
使用内置的达尔文基金会图书馆
斯威夫特3
extension Double {
func round(to places: Int) -> Double {
let divisor = pow(10.0, Double(places))
return Darwin.round(self * divisor) / divisor
}
}
用法:
let number:Double = 12.987654321
print(number.round(to: 3))
输出:12.988
我会用
print(String(format: "%.3f", totalWorkTimeInHours))
然后把。3f改成任何你需要的十进制数
Swift 4, Xcode 10
yourLabel.text = String(format:"%.2f", yourDecimalValue)
