NSPredicate Formatting Issue - ios

Question

I'm creating an iOS app where I want the user to be able to search through a UITableView and display results based on a variety of different inputs. I'm using an NSPredicate with multiple conditions separated by "OR" to do this, but for some reason it's only searching with the first condition and none of the others.
Here's how my NSPredicate is formatted:
let searchPredicate = NSPredicate(format: "(SELF.firstName CONTAINS[c]
%#) OR (SELF.lastName CONTAINS[c] %#) OR (SELF.major CONTAINS[c] %#) OR
(SELF.year CONTAINS[c] %#) OR (SELF.gpa CONTAINS[c] %#)",
searchController.searchBar.text!)
My parameters are firstName, lastName, major, year, and gpa. When I type in anything besides the first name in the search bar, no results show up. But typing in a first name does indeed return matches. Why is this happening? Is my NSPredicate formatted incorrectly?

Answer 1

You have five instances of the %# format specifier in your predicate so you need to pass five values. You are only passing one.
You need to repeat searchController.searchBar.text! five times. BTW - assign that to a safely unwrapped variable and repeat that variable five times. It will be less typing.
if let srch = searchController.searchBar.text {
let searchPredicate = NSPredicate(format: "(SELF.firstName CONTAINS[c] %#) OR
(SELF.lastName CONTAINS[c] %#) OR
(SELF.major CONTAINS[c] %#) OR
(SELF.year CONTAINS[c] %#) OR
(SELF.gpa CONTAINS[c] %#)", srch, srch, srch, srch, srch)
...
}

Answer 2

if let text = searchController.searchBar.text, text.characters.count > 0{
var predicates = [NSPredicate]()
predicates.append(NSPredicate(format: "self.firstName CONTAINS[c]",text))
predicates.append(NSPredicate(format: "self.lastName CONTAINS[c]",text))
predicates.append(NSPredicate(format: "self.major CONTAINS[c]",text))
predicates.append(NSPredicate(format: "self.year CONTAINS[c]",text))
predicates.append(NSPredicate(format: "self.gpa CONTAINS[c]",text))
let searchPredicate:NSPredicate = NSCompoundPredicate(orPredicateWithSubpredicates: predicates)
}

Answer 3

Not tested but this should work and is probably the simplest syntax for Swift if all your subpredicates are the same:
if let text = searchController.searchBar.text {
let myCompondPredicate = NSCompoundPredicate(orPredicateWithSubpredicates: ["firstName", "lastName", "major", "year", "gpa"].map {
NSPredicate(format: "%K CONTAINS[c] %#", $0, text)
})
// Do something with myCompondPredicate here..
}

Answer 4

For a simple, static, predicate like this, I would opt for a native Swift approach:
import Foundation
struct Student {
let firstName: String
let lastName: String
let major: String
let gpa: Double
}
extension Student {
func anyFields(contain searchString: String) -> Bool {
return firstName.contains(searchString)
|| lastName.contains(searchString)
|| major.contains(searchString)
|| String(gpa).contains(searchString)
}
// Alternate implementation:
/*
func anyFields(contain searchString: String) -> Bool {
return [firstName, lastName, major, String(gpa)].contains(where: { field in
field.contains(searchString)
})
} */
}
let matchingStudents = students.filter(Student.anyFields(contain:))