// String to Double
let doubleString = "0.0"
let emptyString = ""
let doubleStringVal = (doubleString as NSString).doubleValue
let emptyStringVal = (emptyString as NSString).doubleValue
let doubleStringValue = Double(doubleString)
let emptyStringValue:Double? = Double(emptyString)
// Substring
let str1 = "000003999000"
str1.substringWithRange(Range<String.Index>(start: str1.startIndex, end: str1.endIndex.advancedBy(-3)))
str1.substringWithRange(Range<String.Index>(start: str1.endIndex.advancedBy(-3), end: str1.endIndex))
// String compare
let stocking = "Stocking"
let stOcking = ""
let STOCKING = "STOCKING"
STOCKING.lowercaseString == stocking.lowercaseString //true
STOCKING == stocking //false
stocking.caseInsensitiveCompare(STOCKING) == NSComparisonResult.OrderedSame //true
// Array (important)
let shoppingList = ["Eggs", "Milk"]
//shoppingList[0] = "Bread" // can not assign value to a array element, error
var shoppingList2 = ["Eggs", "Milk"]
var shoppingList2_copy = shoppingList2
shoppingList2_copy[0] = "Bread"
shoppingList2 //["Eggs", "Milk"]
shoppingList2_copy //["Bread", "Milk"]
// Check API availability in iOS
if #available (iOS 8, *) {
}
@available (iOS 9, *)
func myFunc{
//Only work for >= iOS 9
}