How to make sure a string of pure whitespace is invalid with a succinct code in Swift - ios

Question

I am making a section with TextFields and Button("Continue") and then use .disable(isValidAddress) modifier to a whole section to disable the button. The code works well, but I am seeking any solution to make it more succinct with no need to write .hasPrefix() or .hasSuffix() to all parameters one by one.
var isValidAddress: Bool {
if name.hasPrefix(" ") || street.hasPrefix(" ") || city.hasPrefix(" ") || country.hasPrefix(" ") {
return false
} else if name.hasSuffix(" ") || street.hasSuffix(" ") || city.hasSuffix(" ") || country.hasSuffix(" ") {
return false
}
return true
}

Answer 1

var isValidAddress: Bool {
[street, name, city, etc..].reduce(true, { result, text in
if text.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
return false
} else {
return result
}
})
}

Answer 2

You can add them to an array and trim white space and check if empty in a loop
func isValidAddress() -> Bool {
for field in [name, street, city, country] {
if field.trimmingCharacters(in: .whitespaces).isEmpty { return false }
}
return true
}
I used a function here but a computed property works just as well.

Answer 3

If you don't mind moving some complexity into extensions, you can tidy up the call site. This makes it more readable, and less error prone - you can easily add in another field without mistakes for example.
extension String {
func hasPrefixOrSuffix(_ s: String) -> Bool {
hasPrefix(s) || hasSuffix(s)
}
var noSpacesAtEnds: Bool {
!hasPrefixOrSuffix(" ")
}
}
let isValid = [name, street, city, country]
.allSatisfy(\.noSpacesAtEnds)
If you do mean none of them are "all whitespace strings" then:
extension String {
var isNotAllWhitespace: Bool {
!trimmingCharacters(in: .whitespaces).isEmpty
}
}
let isValid = [name, street, city, country]
.allSatisfy(\.isNotAllWhitespace)
One benefit of having named functions for these things is you can test the pieces, so you can write a test to ensure that isNotAllWhitespace works the way you expect. You couldn't if the logic like name.hasPrefix(" ") || street.hasPrefix(" ") is mixed in with your isValidAddress function.