Pros of GRDB.swift

• More comprehensive documentation and extensive guides
• Built-in support for full-text search and custom SQLite extensions
• Stronger focus on type-safety and compile-time checks

Cons of GRDB.swift

• Steeper learning curve due to more advanced features
• Slightly more complex API compared to SQLite.swift's simplicity
• Less widespread adoption in the Swift community

Code Comparison

SQLite.swift:

let db = try Connection("path/to/db.sqlite3")
try db.run("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)")
try db.run("INSERT INTO users (name) VALUES (?)", "Alice")

GRDB.swift:

let dbQueue = try DatabaseQueue(path: "path/to/db.sqlite3")
try dbQueue.write { db in
    try db.create(table: "users") { t in
        t.autoIncrementedPrimaryKey("id")
        t.column("name", .text)
    }
    try db.execute(sql: "INSERT INTO users (name) VALUES (?)", arguments: ["Alice"])
}

Both libraries offer similar functionality for basic SQLite operations, but GRDB.swift provides more advanced features and type-safety at the cost of increased complexity. SQLite.swift focuses on simplicity and ease of use, making it a good choice for smaller projects or developers new to SQLite in Swift. GRDB.swift is better suited for larger, more complex applications that require advanced SQLite features and stronger type-safety guarantees.

Pros of FMDB

• Mature and well-established project with a long history of use in iOS development
• Simple and straightforward API, making it easy to learn and use
• Supports both synchronous and asynchronous operations

Cons of FMDB

• Relies on Objective-C, which may not be ideal for modern Swift-based projects
• Less type-safe compared to SQLite.swift, requiring more manual type casting
• Lacks some advanced features and Swift-specific optimizations

Code Comparison

FMDB:

FMDatabase *db = [FMDatabase databaseWithPath:@"test.db"];
[db open];
[db executeUpdate:@"INSERT INTO users (name) VALUES (?)", @"John"];
FMResultSet *rs = [db executeQuery:@"SELECT * FROM users"];
while ([rs next]) {
    NSString *name = [rs stringForColumn:@"name"];
}

SQLite.swift:

let db = try Connection("test.db")
try db.run(users.insert(name: "John"))
for user in try db.prepare(users) {
    print("name: \(user[name])")
}

The SQLite.swift code is more concise and type-safe, leveraging Swift's language features. FMDB requires more verbose code and manual type handling, but offers a familiar Objective-C style API.

Pros of Realm

• Object-oriented database with a more intuitive API for working with data models
• Better performance for large datasets and complex queries
• Built-in support for real-time synchronization and offline-first capabilities

Cons of Realm

• Steeper learning curve due to its unique architecture and concepts
• Less flexibility in terms of raw SQL queries and database schema modifications
• Larger binary size and potential memory footprint

Code Comparison

SQLite.swift:

let db = try Connection("path/to/db.sqlite3")
let users = Table("users")
let id = Expression<Int64>("id")
let name = Expression<String>("name")
try db.run(users.create { t in
    t.column(id, primaryKey: true)
    t.column(name)
})

Realm:

class User: Object {
    @Persisted(primaryKey: true) var id: Int64
    @Persisted var name: String
}
let realm = try! Realm()
try! realm.write {
    realm.add(User(value: ["id": 1, "name": "John"]))
}

Both SQLite.swift and Realm offer robust solutions for local data storage in Swift applications. SQLite.swift provides a more traditional SQL-based approach with greater flexibility, while Realm offers an object-oriented model with better performance for complex scenarios and built-in synchronization features. The choice between them depends on specific project requirements and developer preferences.

Pros of Fluent

• Supports multiple databases (PostgreSQL, MySQL, SQLite, MongoDB)
• Integrates seamlessly with the Vapor web framework
• Provides a powerful ORM with type-safe query building

Cons of Fluent

• Steeper learning curve due to its broader scope
• May have more overhead for simple SQLite-only projects
• Less focused on SQLite-specific optimizations

Code Comparison

SQLite.swift:

let db = try Connection("path/to/db.sqlite3")
try db.run("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)")
try db.run("INSERT INTO users (name) VALUES (?)", "Alice")

Fluent:

struct User: Model {
    @ID var id: UUID?
    @Field(key: "name") var name: String
}
try await app.databases.use(.sqlite(.file("path/to/db.sqlite3")), as: .sqlite)
try await User.create(on: database)
let user = User(name: "Alice")
try await user.save(on: database)

Summary

SQLite.swift is a lightweight, SQLite-focused library, while Fluent is a more comprehensive ORM supporting multiple databases. SQLite.swift offers simplicity and direct SQLite access, whereas Fluent provides a higher-level abstraction and integrates well with the Vapor ecosystem. Choose based on your project's complexity and database requirements.