关于文件目录的操作和检查

- (NSString *)dataPath:(NSString *)file  
{  
      
    NSString *path = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"badge"];  
    BOOL bo = [[NSFileManager defaultManager] createDirectoryAtPath:path withIntermediateDirectories:YES attributes:nil error:nil];  
    NSAssert(bo,@"创建目录失败");  
      
    NSString *result = [path stringByAppendingPathComponent:file];  
      
    return result;  
      
}

文件目录操作和文件创建（图片）

- (void)viewDidLoad  
{  
    [super viewDidLoad];   
    //此处首先指定了图片存取路径（默认写到应用程序沙盒 中）  
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);  
     
    //并给文件起个文件名  
    NSString *imageDir = [[[paths objectAtIndex:0] stringByAppendingPathComponent:@"163"] stringByAppendingPathComponent:@"songzi"];  
      
    //存放图片的文件夹  
    NSString *imagePath =[imageDir stringByAppendingPathComponent:@"文件名.png"];  
      
    NSData *data = nil;  
      
    //检查图片是否已经保存到本地  
    if([self isExistsFile:imagePath]){  
        data=[NSData dataWithContentsOfFile:imagePath];  
    }else{  
        data = [NSData dataWithContentsOfURL:[NSURL URLWithString: @"网址"]];  
          
        //创建文件夹路径  
        [[NSFileManager defaultManager] createDirectoryAtPath:imageDir withIntermediateDirectories:YES attributes:nil error:nil];  
          
        //创建图片  
        [UIImagePNGRepresentation([UIImage imageWithData:data]) writeToFile:imagePath atomically:YES];           
    }  
    imageView.image = [UIImage imageWithData:data];  
}

检查文件是否存在

NSString *path = [[NSBundle mainBundle] pathForResource:fileName ofType:@""];
if(path==NULL)