You want to update a label's text after a network call completes. Which is the correct way to handle errors and update the UI safely in Swift?

hard📝 Application Q15 of 15

iOS Swift - Networking

URLSession.shared.dataTask(with: url) { data, response, error in
  // Handle error and update label
}

ACheck if error != nil, then update label text inside DispatchQueue.main.async block

BUpdate label text directly inside the completion handler without dispatching

CIgnore error and update label text on background thread

DUse try-catch inside the completion handler to update label

Step-by-Step Solution

Solution:

Step 1: Handle threading and errors for UI updates
Completion handlers run on background threads, so dispatch UI updates to main. First check if error != nil to handle failure (e.g., update label with error message), using DispatchQueue.main.async.
Final Answer:
Check if error != nil, then update label text inside DispatchQueue.main.async block -> Option A
Quick Check:
UI updates on main thread after error check [OK]

Quick Trick: Always update UI on main thread after error check [OK]

Common Mistakes:

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