Converting a value to double always returns sceintific format in Swift-CodePudding

I am getting some coordinates from server in string array. And I am trying to save those coordinates in SQLite Database by splitting and converting them to double value. But some coordinates are getting saved in scientific notations. For example I am getting the following coordinate from server: "-0.0000558,51.3368066" I am splitting the string and converting it to double resulting in the following values: [-5.58e-05,51.3368066] I have tried following solutions but still returning same result:

Double(latLongArr[0])

extension String{
  var doubleValue: Double? {
    return NumberFormatter().number(from: self)?.doubleValue
  }
}

extension String{
  var doubleValue: Double? {
    let numberFormatter = NumberFormatter()
     numberFormatter.allowsFloats = true
     numberFormatter.maximumFractionDigits = 10
     numberFormatter.numberStyle = .decimal
     return numberFormatter.number(from: "\(self)")!.doubleValue
  }
}

I have used the above code but it still returns in scientific format but I need it in normal decimal format. So what is the issue?

CodePudding user response：

The last option is the option I would go for and I believe it works right.

I believe your issue is only when you print to console:

As you can see, the double variable is actually converted properly but just when it is formatted to print to the console it shows it as a scientific notation string.

Your other option besides using doubleValue is to use decimalValue

I suggest putting a breakpoint and checking the actual value of your double than reviewing it from the console output which is a formatted string.

Just for reference, code used in the image above:

let number = "-0.0000558"

let numberFormatter = NumberFormatter()
numberFormatter.numberStyle = .decimal
numberFormatter.maximumFractionDigits = 10
let finalNumber = numberFormatter.number(from: number)

let decimalNumber = finalNumber!.decimalValue
let doubleNumber = finalNumber!.doubleValue

print(decimalNumber)
print(doubleNumber)

CodePudding user response：

I have used the below extension to represent scientific values in the decimal format.

extension String {
    
    func getDecimalValue() -> Decimal{
        return NSNumber(value: Double(self)!).decimalValue
    }
}

Usage:

let numberString = " 5.58e-05"
print(numberString.getDecimalValue())  //0.0000558

Happy Coding

CodePudding user response：

If you want to print your Doubles without scientific notation use String(format: "%.7f", value).

Example:

let value = Double(3.141592)
print(String(format: "%.7", value)

will print 3.1415920.