Quick Answer

Fix incorrect value expressions.

Understanding the Issue

Swift prevents certain values from being used as expressions, especially in statement contexts.

The Problem

This code demonstrates the issue:

Swift Error 
5 + 3 // Warning as standalone statement

The Solution

Here's the corrected code:

Swift Fixed 
// Solution 1: Use result
let sum = 5 + 3
print(sum)

// Solution 2: Wrap in a function
func calculate() -> Int {
    return 5 + 3
}

// Solution 3: Use @discardableResult
@discardableResult func add(_ a: Int, _ b: Int) -> Int {
    return a + b
}
add(5, 3)

// Solution 4: Make it useful
if 5 + 3 == 8 {
    print("Math works")
}

Key Takeaways

Ensure all expressions are used meaningfully or produce side effects.