沙盒路径、拼接路径、将字符串，二进制Data、照片写入到文件中或读取

    //***************寻找路径*******

    //沙盒路径

    //    NSString *sandBoxPath = NSHomeDirectory();

    //    NSLog(@"%@",sandBoxPath);

    //拼接路径两种方法

    //[sandbox stringByAppendingPathComponent:@"Document"];

    //[sandbox stringByAppendingString:@"/Documents"];

    

    //获取document路径的两种方法

    //1⃣️NSString *documentPath = [sandBoxPath stringByAppendingPathComponent:@"document"];

    //2⃣️NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES)lastObject];

    //寻找系统文件的路径 例如图片的路径

    //NSString *imagepath = [[NSBundle mainBundle]pathForResource:@"1" ofType:@"png"];

    

    //*********将字符串、二进制、图片文件写入相应路径下*******

    NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES)lastObject];

    //字符串写入到相应的路径stringPath

    NSString *strPath = [documentPath stringByAppendingPathComponent:@"str.txt"];

    NSError *error;

    [@"123" writeToFile:strPath atomically:YES encoding:NSUTF8StringEncoding error:&error];

    //读取相应路径的内容

    NSString *str = [NSString stringWithContentsOfFile:strPath encoding:NSUTF8StringEncoding error:&error];

    

    

    //将str转成data保存起来 读取

    [[str dataUsingEncoding:NSUTF8StringEncoding] writeToFile:strPath atomically:YES];

    NSData *data = [NSData dataWithContentsOfFile:strPath];

    

    

    NSString *imagePath = [[NSBundle mainBundle]pathForResource:@"image" ofType:@"png"];

    UIImage *image = [UIImage imageWithContentsOfFile:imagePath];

    //将照片转换成NSData

    NSData *imageData = UIImageJPEGRepresentation(image, 0.1);