ios 数据持久化的三种方式

IOS常用的三种本地数据持久化方式:

1：属性序列化列表 存储到文件 plist；

2：归档序列化，对模型数据进行归档；

3：本地数据库存储，嵌入式sqlite；

其实这三种方式都是把数据存储到本地文件里边，只是实现方式和使用的场景不同而已，复杂程度从上到下增加。

除此之外，还有一种方式存储数据，就是使用NSUserDefaults，它已键值对的形式记录应用程序的全局设置，其实settings.bundle里边的数据就是存在NSUserDefaults的。

主要代码如下：

方式一：plist

//先获取plist文件路径
NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDirectory = [path objectAtIndex:0];
    filePath = [documentDirectory stringByAppendingPathComponent:@"xxx.plist"];
//把数据写入plist
NSArray *arr = [[NSArray allocl] initWithObjects:A,B,C,nil];
[arr writeToFile:self.filePath atomically:YES];

//从plist取数据
NSMutableArray *arr = [[NSMutableArray alloc] initWithContentsOfFile:filePath];

方式二：archiver

//创建继承NSCoding,NSCopying协议的数据模型User，必须实现以下三个方法：
@synthesize passport;
@synthesize password;
@synthesize nickname;
@synthesize remark;

- (void)encodeWithCoder:(NSCoder *)encoder{
    [encoder encodeObject:passport forKey:kPassportKey];
    [encoder encodeObject:password forKey:kPasswordKey];
    [encoder encodeObject:nickname forKey:kNicknameKey];
    [encoder encodeObject:remark forKey:kRemarkKey];
}

- (id)initWithCoder:(NSCoder *)decoder{
    if (self=[super init]) {
        self.passport = [decoder decodeObjectForKey:kPassportKey];
        self.password = [decoder decodeObjectForKey:kPasswordKey];
        self.nickname = [decoder decodeObjectForKey:kNicknameKey];
        self.remark = [decoder decodeObjectForKey:kRemarkKey];
    }
    return self;
}

- (id)copyWithZone:(NSZone *)zone{
    User *copy = [[[self class] allocWithZone:zone] init];
    passport = [self.passport copy];
    password = [self.password copy];
    nickname = [self.nickname copy];
    remark = [self.remark copy];
    return copy;
}

//获取归档文件
- (NSString *)dataFilePath{
    NSArray *arr = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    return [(NSString *)[arr objectAtIndex:0] stringByAppendingPathComponent:@"archiver"];
}

//初始化数据模型并写入归档文件
User *user = [[User alloc] init];
    user.passport = @"alec030711";
    user.password = @"abcd";
    user.nickname = @"alecchyi";
    user.remark = @"fuck";

    NSMutableData *data = [[NSMutableData alloc] init];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
    [archiver encodeObject:user forKey:@"kData"];
    [archiver finishEncoding];
    [data writeToFile:[self dataFilePath] atomically:YES];
    [archiver release];
    [data release];
    [user release];

//从归档文件读数据
NSMutableData *data = [[NSMutableData alloc] initWithContentsOfFile:[self dataFilePath]];
    NSKeyedUnarchiver *unArchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
    User *user = [unArchiver decodeObjectForKey:@"kData"];
    [unArchiver finishDecoding];

    [data release];
    [unArchiver release];

 方式三：sqlite

sqlite3 *database;
//打开数据库，没有则创建
if (sqlite3_open([数据库文件路径 UTF8String], &database) != SQLITE_OK) {
    sqlite3_close(database);
}
//创建表
char *errorStr;
NSString *createTable = @"drop table if exists users;create table if not exists users (id integer primary key,nickname text);";
if (sqlite3_exec(database,[createTable UTF8String],NULL,NULL,&errorStr)!=SQLITE_OK) {
    sqlite3_close(database);
}
//插入数据
for (int x=1; x<5; x++) {
    NSString *insert = [[NSString alloc] initWithFormat:@"insert or replace into users (id,nickname) values (%d,'ruby%d')",x,x];
    if (sqlite3_exec(database,[insert UTF8String],NULL,NULL,&errorStr)!=SQLITE_OK) {
        sqlite3_free(database);
    }
    [insert release];
}
//查询表数据
NSString *query = @"select nickname,id from users";
sqlite3_stmt *statememt;
if (sqlite3_prepare_v2(database,[query UTF8String],-1,&statememt,nil)==SQLITE_OK) {
    while (sqlite3_step(statememt)==SQLITE_ROW) {
        char *rowData = (char *)sqlite3_column_text(statememt,0);
        NSString *nickname = [[NSString alloc] initWithUTF8String:rowData];
        [nickname release];
    }
}
sqlite3_finalize(statememt);
//关闭数据库
sqlite3_close(database);

//关键就这几个方法和几个语句：sqlite3_open, sqlite3_exec,sqlite3_prepare_v2  sqlite3_step sqlite_finalize,sqlite3_close。

 方式三需要引入libsqlite3.lib，由于sqlite数据库是C实现的，存储也是C形式存储，所以在取出数据时需要用UTF8String转换成objecitve-c形式的字符串