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