在SQLITE swift中与不透明指针作斗争

Question

嗨，我是swift的新手，正在尝试为我的a级别编码项目添加数据库。我似乎无法让不透明的指针在没有错误的情况下工作。我使用过教程，但总是会出现同样的错误。我得到的错误：

Expected member name or constructor call after type name on line 3

Cannot convert value of type 'UnsafeMutablePointer<OpaquePointer?.Type>' to expected argument type 'UnsafeMutablePointer<OpaquePointer?>' On line 9

Cannot convert return expression of type 'OpaquePointer?.Type' to return type 'OpaquePointer?' On line 12

var dbURL = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String

func createDatabase() -> OpaquePointer?{
var db = OpaquePointer?
let url = NSURL(fileURLWithPath: dbURL)

if let pathComponent = url.appendingPathComponent("Database.sqlite"){
let filePath = pathComponent.path
if sqlite3_open(filePath, &db) == SQLITE_OK{
print("successfully opened database")

return db
}

}

}

Answer 1

将var db = OpaquePointer?更改为var db : OpaquePointer?

在函数末尾添加return nil。

Answer 2

您需要在第3行使用冒号而不是等号。