iphone document 图片存储和读取
存：

  //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 *uniquePath=[[paths objectAtIndex:0] stringByAppendingPathComponent:@"pin.png"];    BOOL blHave=[[NSFileManager defaultManager] fileExistsAtPath:uniquePath];    if (blHave) {        NSLog(@"already have");        return ;    }    //此处的方法是将图片写到Documents文件中 如果写入成功会弹出一个警告框,提示图片保存成功    NSString *strPathOld = [[NSBundle mainBundle] pathForResource:@"pin" ofType:@"png"];    NSData *data = [NSData dataWithContentsOfFile:strPathOld];    BOOL result = [data writeToFile:uniquePath atomically:YES];    if (result) {        NSLog(@"success");    }else {        NSLog(@"no success");    } 

  NSFileManager *fileManager = [NSFileManager defaultManager];    NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory,                                                                          NSUserDomainMask, YES);    NSString *documentsDirectory = [paths objectAtIndex:0];    NSString *filePath2 = [documentsDirectory stringByAppendingPathComponent:@"pin.png"];    UIImage *img = [UIImage imageWithContentsOfFile:filePath2];    [image setImage:img];    NSLog(@"图片：：：：：：：：：%@",image.image); 

 NSFileManager* fileManager=[NSFileManager defaultManager];    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);        //文件名    NSString *uniquePath=[[paths objectAtIndex:0] stringByAppendingPathComponent:@"pin.png"];    BOOL blHave=[[NSFileManager defaultManager] fileExistsAtPath:uniquePath];    if (!blHave) {        NSLog(@"no  have");        return ;    }else {        NSLog(@" have");        BOOL blDele= [fileManager removeItemAtPath:uniquePath error:nil];        if (blDele) {            NSLog(@"dele success");        }else {            NSLog(@"dele fail");        }            }