数据持久化保存

- (NSString *)cachesTestPathWithFileName:(NSString *)fileName{

    //缓存文件夹路劲

    NSString *caches = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)[0];

    //在caches中添加一个子文件夹（目录）

    NSString *cachesTestPath = [caches stringByAppendingPathComponent:@"test"];
    //创建中间目录
    //这是一个单利
    NSFileManager *fileManager = [NSFileManager defaultManager];
    //判断文件夹是否存在
    if (![fileManager fileExistsAtPath:cachesTestPath]) {
        //创建文件夹
        [fileManager createDirectoryAtPath:cachesTestPath withIntermediateDirectories:YES attributes:nil error:nil];
    }
    //拼接文件名字
   return [caches stringByAppendingPathComponent:fileName];
}

读写文件，text(NSString ),json,plist(NSDictionary,NSArray),png,zip,(NSData)

- (void)viewDidLoad {
    [super viewDidLoad];
    

1.字符串读写文件

    //NSString 一般读写成：.txt .json .xml .h .m 等后缀文件
    //获取文件沙盒路劲
    NSString *strPath = [self cachesTestPathWithFileName:@"str.txt"];
    NSLog(@"%@",strPath);
    //写文件
    BOOL ret = [@"hello world!" writeToFile:strPath atomically:NO encoding:NSUTF8StringEncoding error:nil];
    if (ret) {
        NSLog(@"完成");
    }
    //读取文件
    NSString *outStr = [NSString stringWithContentsOfFile:strPath encoding:NSUTF8StringEncoding error:nil];
    NSLog(@"%@",outStr);
    

2.NSArray文件读写

    //读写成plist
    NSString *arrPath = [self cachesTestPathWithFileName:@"arr.plist"];
    //写入本地
    BOOL arrret = [@[@"12334"] writeToFile:arrPath atomically:NO];
    if (arrret) {
        NSLog(@"完成");
    }
    //读取数组
    NSArray *outArr = [NSArray arrayWithContentsOfFile:arrPath];
    NSLog(@"%@",outArr);
    

3.字典的读写

    //NSDictionary 一般读写成plist文件
    NSString *dicPath = [self cachesTestPathWithFileName:@"dic.plist"];
    //写入本地
    BOOL dicRet = [@{@"abc":@"123456"} writeToFile:dicPath atomically:NO];
    if (dicRet) {
        NSLog(@"成功");
    }
    //读取字典
    NSDictionary *dicOut = [NSDictionary dictionaryWithContentsOfFile:dicPath];
    NSLog(@"%@",dicOut);
    
    //NSData 二进制读写文件
    NSString *password = @"123456";
    NSData *data = [password dataUsingEncoding:NSUTF8StringEncoding];
    //
    NSString *dataPath = [self cachesTestPathWithFileName:@"cat.png"];
    //二进制写入文件
    [data writeToFile:dataPath atomically:NO];
    //读取二进制文件
    NSData *dataOut = [NSData dataWithContentsOfFile:dataPath];
    NSString *strDataOut = [[NSString alloc]initWithData:dataOut encoding:NSUTF8StringEncoding];
    NSLog(@"%@",strDataOut);
   

4.轻量级存储数据

  为plist文件,存在沙盒路径下Library下的preferences中

     //获取单利对象

    NSUserDefaults *UD = [NSUserDefaults standardUserDefaults];
    //写入数据
    [UD setObject:@[@"魁拔"] forKey:@"kuiba"];
    [UD setBool:YES forKey:@"bool"];
    [UD setFloat:3.14159256 forKey:@"pi"];
    
    //执行同步
    [UD synchronize];
    //获取数据
    NSLog(@"%f",[UD floatForKey:@"pi"]);

}