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MMKV is an efficient, small, easy-to-use mobile key-value storage framework used in the WeChat application. It's currently available on both iOS and Android.

MMKV for iOS

Features

• Efficient. MMKV uses mmap to keep memory synced with file, and protobuf to encode/decode values, making the most of iOS to achieve best performance.

• Easy-to-use. You can use MMKV as you go, no configurations needed. All changes are saved immediately, no synchronize calls needed.

• Small.

  • A handful of files: MMKV contains encode/decode helpers and mmap logics and nothing more. It's really tidy.
  • Less than 30K in binary size: MMKV adds less than 30K per architecture on App size, and much less when zipped (ipa).

Getting Started

Installation Via CocoaPods:

1. Install CocoaPods;
2. Open terminal, cd to your project directory, run pod repo update to make CocoaPods aware of the latest available MMKV versions;
3. Edit your Podfile, add pod 'MMKV' to your app target;
4. Run pod install;
5. Open the .xcworkspace file generated by CocoaPods;
6. Add #import <MMKV/MMKV.h> to your source file and we are done.

For other installation options, see iOS Setup.

Quick Tutorial

You can use MMKV as you go, no configurations needed. All changes are saved immediately, no synchronize calls needed.

MMKV *mmkv = [MMKV defaultMMKV];
    
[mmkv setBool:YES forKey:@"bool"];
BOOL bValue = [mmkv getBoolForKey:@"bool"];
    
[mmkv setInt32:-1024 forKey:@"int32"];
int32_t iValue = [mmkv getInt32ForKey:@"int32"];
    
[mmkv setObject:@"hello, mmkv" forKey:@"string"];
NSString *str = [mmkv getObjectOfClass:NSString.class forKey:@"string"];

Full tutorials can be found here.

Performance

Writing random int for 10000 times, we get this chart:

For more benchmark data, please refer to our benchmark.

MMKV for Android

Features

• Efficient. MMKV uses mmap to keep memory synced with file, and protobuf to encode/decode values, making the most of Android to achieve best performance.

  • Multi-Process concurrency: MMKV supports concurrent read-read and read-write access between processes.

• Easy-to-use. You can use MMKV as you go. All changes are saved immediately, no sync, no apply calls needed.

• Small.

  • A handful of files: MMKV contains process locks, encode/decode helpers and mmap logics and nothing more. It's really tidy.
  • About 60K in binary size: MMKV adds about 60K per architecture on App size, and much less when zipped (apk).

Getting Started

Installation Via Maven

Add the following lines to build.gradle on your app module:

dependencies {
    implementation 'com.tencent:mmkv:1.0.10'
    // replace "1.0.10" with any available version
}

For other installation options, see Android Setup.

Quick Tutorial

You can use MMKV as you go. All changes are saved immediately, no sync, no apply calls needed.
Setup MMKV on App startup, say your MainActivity, add these lines:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    String rootDir = MMKV.initialize(this);
    System.out.println("mmkv root: " + rootDir);
    //……
}

MMKV has a global instance, that can be used directly:

import com.tencent.mmkv.MMKV;
    
MMKV kv = MMKV.defaultMMKV();

kv.encode("bool", true);
boolean bValue = kv.decodeBool("bool");

kv.encode("int", Integer.MIN_VALUE);
int iValue = kv.decodeInt("int");

kv.encode("string", "Hello from mmkv");
String str = kv.decodeString("string");

MMKV also supports Multi-Process Access. Full tutorials can be found here Android Tutorial.

Performance

Writing random int for 1000 times, we get this chart:

For more benchmark data, please refer to our benchmark.

License

MMKV is published under the BSD 3-Clause license. For details check out the LICENSE.TXT.

Contributing

If you are interested in contributing, check out the CONTRIBUTING.md, also join our Tencent OpenSource Plan.

FAQ & Feedback

Check out the FAQ first. Should there be any questions, don't hesitate to create issues.