maximum/minimum on incrementing buttons - swift

Question

I'm fairly new to Xcode/Swift and am wondering how to set a maximum and minimum for amounts that result in a plus and minus button being touched. My existing code is below. The notifyBeforeAvailabilty I want to go from 1-20 and the ratePerMinute I want to go from $0.00 to $15.00.
var notifyBeforeAvailability: Int!
var ratePerMin: Float!
notifyBeforeAvailability = 1
updateNotifyBeforeAvailability()
ratePerMin = 0.10
updateRatePerMin()
#IBAction func notifyBeforeAvailabilityPlus(sender: AnyObject) {
notifyBeforeAvailability = notifyBeforeAvailability + 1
updateNotifyBeforeAvailability()
}
#IBAction func notifyBeforeAvailabilityMinus(sender: AnyObject) {
notifyBeforeAvailability = notifyBeforeAvailability - 1
updateNotifyBeforeAvailability()
}
func updateNotifyBeforeAvailability() {
lblNotifyTime.text = String(notifyBeforeAvailability) + "min"
}
#IBAction func ratePerMinPlus(sender: AnyObject) {
ratePerMin = ratePerMin + 0.10
updateRatePerMin()
}
#IBAction func ratePerMinMinus(sender: AnyObject) {
ratePerMin = ratePerMin - 0.10
updateRatePerMin()
}
func updateRatePerMin() {
let currentValue = ratePerMin
let current_string = String.localizedStringWithFormat("%.2f", currentValue)
lblYourRate.text = "$" + current_string
}

Answer 1

You can use min & max for clamping values. Something like:
notifyBeforeAvailability = min(max(1, notifyBeforeAvailability + 1), 20)
// In this example 1 & 20 are your bounds
// set the others accordingly...
Also, you could avoid to format numbers yourself by utilizing NSNumberFormatter
By the way... In case you're using UIStepper controls, there are minimumValue & maximumValue (along with a stepValue) properties that handle limits for you...

Answer 2

The Alladinian's answer is right, but I prefer use didSet in var and from there call the functions.
var notifyBeforeAvailability : Int = 1 {
didSet {
if oldValue < 1 {
self.notifyBeforeAvailability = 1
}
if oldValue > 20 {
self.notifyBeforeAvailability = 20
}
updateNotifyBeforeAvailability()
}
}
var ratePerMin : Float = 0.10 {
didSet{
if newValue < 0.0{
self.ratePerMin = 0.0
}
if newValue > 15.0 {
self.ratePerMin = 15.0
}
print(newValue)
updateRatePerMin()
}
}
#IBAction func notifyBeforeAvailabilityPlus(sender: AnyObject) {
notifyBeforeAvailability += 1
}
#IBAction func notifyBeforeAvailabilityMinus(sender: AnyObject) {
notifyBeforeAvailability -= 1
}
func updateNotifyBeforeAvailability() {
lblNotifyTime.text = String(notifyBeforeAvailability) + "min"
}
#IBAction func ratePerMinPlus(sender: AnyObject) {
ratePerMin += 0.10
}
#IBAction func ratePerMinMinus(sender: AnyObject) {
ratePerMin -= 0.10
}
func updateRatePerMin() {
let currentValue = ratePerMin
let current_string = String.localizedStringWithFormat("%.2f", currentValue)
lblYourRate.text = "$" + current_string
}