Q: How to split numeric and substring from main string in SWIFT? I have a case where I need to separate the numeric value and other substring from the main given string. 
Suppose the main string is 350.55kph.
Then my desired result is 350.55 as a numeric value and kph is other substring. 
Can someone help me with this?

A: Here is how:
let string = "350kph"
let stringArray = string.components(separatedBy: CharacterSet.decimalDigits.inverted)
for item in stringArray {
    if let integer = Int(item) {
        print("integer: \(integer)")
    }
}

Note: This would work for strings containing multiple Int eg: "350km per 2hr". You would only require:
let string = "350kph"
let integer = Int(string.components(separatedBy: CharacterSet.decimalDigits.inverted).joined())
print("integer: \(integer)")

Okay I saw your edits, here's how to decimals, (there are other ways too):
let string = "350.55kph"
let components = string.components(separatedBy: ".")
let decimalPart = Int(components.last!.components(separatedBy: CharacterSet.decimalDigits.inverted).joined()) ?? 0
let double = Double("\(components.first ?? "0").\(decimalPart)")
print(decimalPart,"double: \(double)")

Other way: You can modify the CharecterSet to achieve the desired result.

A: A regular expression would probably work. Something like ([0-9.]+)([A-Za-z]+) which will extract it into two groups: 1 one with numeric part, the other with the unit.
There's a few options here on how to work with those groups: Swift 3 - How do I extract captured groups in regular expressions?
