逍遙文工作室

一直對儲存和讀取影像感到恐懼，不過有機會來嘗試一下，就藉此突破心魔吧！其實還滿容易做到，行動裝置就好比一般電腦一樣！

程式碼功用是先建立路徑，我以Documents這個資料夾為起始點，想要在裡頭再產生1、2、3⋯⋯等資料夾，然後把影像分門別類塞到那些資料夾中。

儲存影像可以這麼寫：

//儲存檔案
    // 設定序號
    NSInteger serial = [[HMAppDelegate sharedAppDelegate].serial intValue] + 1;
    // 建立資料夾
    NSString *documentsDirectory = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
    NSString *targetDirectory = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%i", serial]];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    if (![fileManager fileExistsAtPath:targetDirectory]) {
        [fileManager createDirectoryAtPath:targetDirectory withIntermediateDirectories:YES attributes:nil error:nil];
    }
    UIImage *image = [[UIImage alloc] initWithCGImage:asset.defaultRepresentation.fullScreenImage];
    NSData *imageData = UIImageJPEGRepresentation(image, 1.0);
    NSString *imageNameFS = [NSString stringWithFormat:@"happy image.jpg"];
    [imageData writeToFile:[targetDirectory stringByAppendingPathComponent:imageNameFS] atomically:YES];

讀取影像可以這麼做：

//讀取檔案
    NSString *documentsDirectory = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
    NSString *targetDirectory = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%i", serial]];
    NSString *imageNameFS = [NSString stringWithFormat:@"happy image.jpg"];
    UIImage *imagex = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL fileURLWithPath:[targetDirectory stringByAppendingPathComponent:imageNameFS]]]];

想知道是否順利儲存影像，可以在模擬器上跑，列印出路徑變數，然後打開終端機，輸入指令：

open “/Users/happyman/Library/Application Support/iPhone Simulator/7.0/Applications/93BE4DBB-02C6-46DD-A9F5-188023F11929/Documents/1″

記得要在引號內貼上路徑，因為路徑可能會有空白。

刪除影像可以如此：

//刪除檔案
    NSString *documentsDirectory = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
    NSString *targetDirectory = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%i", serial]];
    NSString *imageNameFS = [NSString stringWithFormat:@"happy image.jpg"];
    [[NSFileManager defaultManager] removeItemAtPath:[targetDirectory stringByAppendingPathComponent:imageNameFS] error:nil];

以下程式碼很神奇：

    NSString *documentsDirectory = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
    NSString *targetDirectory = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"H/A/P/P/Y"]];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    if (![fileManager fileExistsAtPath:targetDirectory]) {
        [fileManager createDirectoryAtPath:targetDirectory withIntermediateDirectories:YES attributes:nil error:nil];
    }

它會陸續幫我建立HAPPY五個層級的資料夾呢！關鍵在於withIntermediateDirectories要設YES！

註：我發現影像可以儲存成JPG和PNG，分別使用UIImageJPEGRepresentation(image, 1.0)和UIImagePNGRepresentation(image)，後者可以儲存透明像素，前者若儲存有著透明像素影像，透明會變成白色喔！

參考：iOS 檔案寫入、讀取、刪除。