🔁 Swift Arrays Loop – Complete Tutorial (Beginner → Interview Level)

Looping through arrays is a core skill in Swift for iOS/macOS development, data handling, and UI lists (TableView / CollectionView).

Swift provides multiple clean and safe ways to loop through arrays.

1️⃣ Basic for-in Loop ⭐ (Most Common)

✔ Simple
✔ Clean
✔ Interview-friendly

2️⃣ Loop Using Index ⭐

📌 Use when index is required
⚠️ Risky if array size changes

3️⃣ Loop Using indices (Safe Way ⭐⭐)

✔ Safer than 0..<count
✔ Recommended by Swift style guide

4️⃣ forEach Loop ⭐

Shorter syntax:

📌 Functional style
❌ Cannot use break or continue

5️⃣ Loop with enumerated() ⭐⭐ (Index + Value)

✔ Very common in interviews
✔ Best when you need both index & value

6️⃣ while Loop with Array

📌 Less common
✔ Useful for conditional looping

7️⃣ repeat-while Loop

✔ Executes at least once

8️⃣ Loop with Condition (Filtering Inside Loop)

9️⃣ Loop with break and continue ⭐

📌 ❌ Not allowed in forEach

🔟 Reverse Looping ⭐

1️⃣1️⃣ Nested Loop with Arrays

1️⃣2️⃣ Common Looping Mistakes ❌

❌ Index out of range
❌ Using forEach when break is needed
❌ Using while unnecessarily
❌ Modifying array while looping

🔄 Loop Methods Comparison (Interview ⭐)

📌 Interview Questions & MCQs

Q1. Best way to loop array values?

A) while
B) forEach
C) for-in
D) repeat-while

✅ Answer: C

Q2. Which loop gives index + value?

A) for-in
B) enumerated()
C) indices
D) map()

✅ Answer: B

Q3. Can we use break inside forEach?

A) Yes
B) No

✅ Answer: B

Q4. Safest way to loop using index?

A) 0..<count
B) indices

✅ Answer: B

Q5. Arrays in Swift are?

A) Reference types
B) Value types

✅ Answer: B

🔥 Real-Life Use Cases

✔ Display list data
✔ API response processing
✔ TableView rows
✔ Validation logic
✔ App business logic

✅ Summary

• Swift offers multiple ways to loop arrays

• for-in is the best & most common

• Use enumerated() for index + value

• Avoid index errors using indices

• forEach is clean but limited

• Must-know topic for Swift interviews