Quick Answer

Fix unknown symbol errors.

Understanding the Issue

This occurs when the compiler encounters an undeclared variable or function name.

The Problem

This code demonstrates the issue:

Swift Error 
print(unknownVariable) // Error

The Solution

Here's the corrected code:

Swift Fixed 
// Solution 1: Declare the variable
let knownVariable = "Hello"
print(knownVariable)

// Solution 2: Check scope
func example() {
    let localVar = "Local"
    print(localVar) // Works
}
// print(localVar) Would fail outside scope

// Solution 3: Import required modules
import Foundation // For NSObject etc.

// Solution 4: Check for typos
let userName = "John"
print(userName) // Not userNamme

Key Takeaways

Ensure all identifiers are properly declared and in scope.