您可以使用Realm.Configuration.fileURL来更改Realm文件路径。如下所示：

let cachesDirectoryPath = NSSearchPathForDirectoriesInDomains(.CachesDirectory, .UserDomainMask, true)[0]
let cachesDirectoryURL = NSURL(fileURLWithPath: cachesDirectoryPath)
let fileURL = cachesDirectoryURL.URLByAppendingPathComponent("Default.realm")

let config = Realm.Configuration(fileURL: fileURL)
let realm = try! Realm(configuration: config)

如果不想在每个示例化领域中指定fileURL，可以使用Realm.Configuration.defaultConfiguration。如果将配置对象设置为defaultConfiguration，则Realm()将使用该配置作为默认值。

Realm.Configuration.defaultConfiguration = config
let realm = Realm()

另请参阅... https://realm.io/docs/swift/latest/#realm-configuration

我更新了kishikawa对Swift 5和Realm 10的回答。我在AppDelegate的“didFinishLaunchingWithOptions”中调用了这个函数：

private func setRealmDefaultConfig() {
    let cachesDirectoryPath = NSSearchPathForDirectoriesInDomains(.cachesDirectory, .userDomainMask, true)[0]
    let cachesDirectoryURL = NSURL(fileURLWithPath: cachesDirectoryPath)
    let fileURL = cachesDirectoryURL.appendingPathComponent("Default.realm")
    let config = Realm.Configuration(fileURL: fileURL)
    Realm.Configuration.defaultConfiguration = config
}

请记住，显然只有在没有新配置的情况下进行示例化时才会使用“DefaultConfiguration”：Realm()