下面是我以前如何将一个浮点数截断到小数点后两位
NSLog(@" %.02f %.02f %.02f", r, g, b);
我查了文档和电子书，但还没找到答案。谢谢!
当前回答
@infix func ^(left:Double, right: Int) -> NSNumber {
let nf = NSNumberFormatter()
nf.maximumSignificantDigits = Int(right)
return nf.numberFromString(nf.stringFromNumber(left))
}
let r = 0.52264
let g = 0.22643
let b = 0.94837
println("this is a color: \(r^3) \(g^3) \(b^3)")
// this is a color: 0.523 0.226 0.948
其他回答
import Foundation
extension CGFloat {
var string1: String {
return String(format: "%.1f", self)
}
var string2: String {
return String(format: "%.2f", self)
}
}
使用
let offset = CGPoint(1.23, 4.56)
print("offset: \(offset.x.string1) x \(offset.y.string1)")
// offset: 1.2 x 4.6
Swift 4 Xcode 10更新
extension Double {
var asNumber:String {
if self >= 0 {
let formatter = NumberFormatter()
formatter.numberStyle = .none
formatter.percentSymbol = ""
formatter.maximumFractionDigits = 2
return "\(formatter.string(from: NSNumber(value: self)) ?? "")"
}
return ""
}
}
@infix func ^(left:Double, right: Int) -> NSNumber {
let nf = NSNumberFormatter()
nf.maximumSignificantDigits = Int(right)
return nf.numberFromString(nf.stringFromNumber(left))
}
let r = 0.52264
let g = 0.22643
let b = 0.94837
println("this is a color: \(r^3) \(g^3) \(b^3)")
// this is a color: 0.523 0.226 0.948
使用以下方法
let output = String.localizedStringWithFormat(" %.02f %.02f %.02f", r, g, b)
println(output)
Swift2示例:iOS设备的屏幕宽度格式化浮点数去除小数
print(NSString(format: "Screen width = %.0f pixels", CGRectGetWidth(self.view.frame)))
