導語
最近在寫swift網(wǎng)絡請求使用二級緩存的時候匹表，用到了SQLite3來保存緩存數(shù)據(jù)，以前都是在oc中使用宣鄙，這次在swift3.1中使用袍镀，遇到了不少坑，分享給大家冻晤。
1苇羡、打開數(shù)據(jù)庫，創(chuàng)建表
mutating func openSQLiteDataBase(path: String) -> Bool {
if let _ = db {
return true
}
//獲取cache路徑
guard let basePath = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.cachesDirectory,FileManager.SearchPathDomainMask.userDomainMask, true).last else { return false }
let finalPath = basePath + "/\(path)"
//將string轉(zhuǎn)換成cString
let cStr = finalPath.cString(using: .utf8)
//返回openDB是否成功
return sqlite3_open(cStr, &db) == SQLITE_OK
}
func creatTable() -> Bool {
let creatTb = "create table if not exists netWorkCache (key text, size integer, inline_data blob,primary key(key));"
//執(zhí)行SQL語句
return execSQL(SQL:creatTb)
}
func execSQL(SQL: String?) -> Bool {
guard let sqlstr = SQL else { return false }
let cSQL = sqlstr.cString(using: .utf8)
let error :UnsafeMutablePointer<UnsafeMutablePointer<Int8>?>? = nil
let result = sqlite3_exec(db, cSQL, nil, nil, error)
if let err = error {
print("sqlite exec error \(result),\(err)")
}
return result == SQLITE_OK
}
2鼻弧、插入數(shù)據(jù)（開始又坑了）
首先是這個key String 類型,轉(zhuǎn)換為cString來綁定數(shù)據(jù)時设江，經(jīng)常寫不進去，db表里面key這個值有時有數(shù)據(jù)攘轩，有時是空的叉存，有時只有不全的key，到處找資料度帮，修改SQL語句歼捏，也不行啊。最后在http://stackoverflow.com上找到了解決方法（還是國外牛人多氨颗瘛）瞳秽，解決方式：把String先轉(zhuǎn)換成NSString，再轉(zhuǎn)換成cString 這樣就寫進去了冕屯，我勒個去寂诱，完全不知道為什么這樣改了就能成功綁定了（有知道原因的大神請給我說說原因啊）安聘。Data類型數(shù)據(jù)也是同理痰洒。
func insertDataToDist(key: String, size: Int, data: Data) -> Bool {
let insetSql = "insert or replace into netWorkCache (key, size, inline_data) values (?1, ?2, ?3)"
guard let stmt = dbPrepareStmt(sql: insetSql) else { return false }
let nsdata = data as NSData
let nskey = key as NSString
sqlite3_bind_text(stmt, 1, nskey.utf8String, -1, nil)
sqlite3_bind_int(stmt, 2, Int32(size))
sqlite3_bind_blob(stmt, 3, nsdata.bytes, Int32(nsdata.length), nil)
return sqlite3_step(stmt) == SQLITE_DONE
}
3瓢棒、查找數(shù)據(jù)(同樣需要先轉(zhuǎn)成NSString，再轉(zhuǎn)換成cString)
func getDbItem(key: String) -> NetCacheModel? {
let searchSql = "select key, size, inline_data from netWorkCache where key = ?1"
guard let stmt = dbPrepareStmt(sql: searchSql) else { return nil }
let nskey = key as NSString
sqlite3_bind_text(stmt, 1, nskey.utf8String, -1, nil)
if sqlite3_step(stmt) == SQLITE_ROW {
return dbGetItemFormStmt(stmt: stmt)
}else {
return nil
}
}
func dbPrepareStmt(sql: String?) -> OpaquePointer? {
guard let sqlStr = sql else { return nil }
var stmt: OpaquePointer? = nil
if sqlite3_prepare_v2(db, sqlStr.cString(using: .utf8), -1, &stmt, nil) == SQLITE_OK {
return stmt
}else {
return nil
}
}
func dbGetItemFormStmt(stmt:OpaquePointer) -> NetCacheModel? {
let size = sqlite3_column_int(stmt, 1)
let databytes = sqlite3_column_bytes(stmt, 2)
guard let key = sqlite3_column_text(stmt, 0),
let data = sqlite3_column_blob(stmt, 2) else { return nil }
//取到data數(shù)據(jù)bytes丘喻，然后獲取length脯宿，初始化data
let result = Data.init(bytes: data, count: Int(databytes))
return NetCacheModel(key: String.init(cString: key), size: Int(size), data: result)
}
文章就先寫到這里了，分享給同樣遇到坑的朋友泉粉。
