Swift: How do I create a predicate with an Int value?

Question

I am getting an EXC-BAD-ACCESS error on this statement:

var thisPredicate = NSPredicate(format: "(sectionNumber == %@"), thisSection) 

thisSection has an Int value of 1 and displays the value 1 when I hover over it. But in the debug area I see this:

thisPredicate = (_ContiguousArrayStorage ...) 

Another predicate using a String shows as ObjectiveC.NSObject Why is this happening?

Answer 1

You will need to change %@ for %i and remove the extra parenthesis:

Main problem here is that you are putting an Int where it's expecting an String.

Here's an example based on this post:

class Person: NSObject {     let firstName: String     let lastName: String     let age: Int      init(firstName: String, lastName: String, age: Int) {         self.firstName = firstName         self.lastName = lastName         self.age = age     }      override var description: String {         return "\(firstName) \(lastName)"     } }  let alice = Person(firstName: "Alice", lastName: "Smith", age: 24) let bob = Person(firstName: "Bob", lastName: "Jones", age: 27) let charlie = Person(firstName: "Charlie", lastName: "Smith", age: 33) let quentin = Person(firstName: "Quentin", lastName: "Alberts", age: 31) let people = [alice, bob, charlie, quentin]   let thisSection = 33 let thisPredicate = NSPredicate(format: "age == %i", thisSection)  let _people = (people as NSArray).filteredArrayUsingPredicate(thisPredicate) _people 

Another workaround would be to make thisSection's value an String, this can be achieved by String Interpolation or via description property of the Int.. lets say:

Changing:

let thisPredicate = NSPredicate(format: "age == %i", thisSection) 

for

let thisPredicate = NSPredicate(format: "age == %@", thisSection.description) 

or

let thisPredicate = NSPredicate(format: "age == %@", "\(thisSection)") 

of course, you can always bypass this step and go for something more hardcoded (but also correct) as:

let thisPredicate = NSPredicate(format: "sectionNumber == \(thisSection)") 

But take into account that for some weird reason String Interpolation (this kind of structure: "\(thisSection)") where leading to retain cycles as stated here

Answer 2

When your data is safe or sanitized, you might try String Interpolation Swift Standard Library Reference. That would look something like this:

let thisSection = 1 let thisPredicate = NSPredicate(format: "sectionNumber == \(thisSection)")