Coding⏱️ 1 min read📅 2026-05-31

How to Fix: Why NSUserDefaults failed to save NSMutableDictionary in iOS?

Q: How do I fix: 🔧 Proven Troubleshooting StepsMethod 1: Using NSKeyedArchiver?

Step 1: Create an instance of NSKeyedArchiver and set the delegate to your view controller or a subclass.

Q: How do I fix: Method 2: Using NSUserDefaults' setObject:forKey:withCoder:?

Step 1: Create an instance of NSData and encode your NSMutableDictionary object using NSKeyedArchiver.

How to save an NSMutableDictionary object in NSUserDefaults using NSArchiver.

Quick Answer: Use NSArchiver to archive the NSMutableDictionary object before saving it in NSUserDefaults.

To save an NSMutableDictionary object in NSUserDefaults, you need to convert the object to a property list (plist) format. The issue arises because NSUserDefaults can only store objects that conform to the NSCoding protocol.

🔧 Proven Troubleshooting Steps

Method 1: Using NSKeyedArchiver

Step 1: Create an instance of NSKeyedArchiver and set the delegate to your view controller or a subclass.

Method 2: Using NSUserDefaults' setObject:forKey:withCoder:

Step 1: Create an instance of NSData and encode your NSMutableDictionary object using NSKeyedArchiver.

By following these steps, you should be able to successfully save your NSMutableDictionary object in NSUserDefaults.

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