Question

我从网址获取图片并保存到文件。我保存和加载的代码：

-(void) saveImage:(UIImage *)image withFileName:(NSString *)imageName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
    if ([[extension lowercaseString] isEqualToString:@"png"]) {
        [UIImagePNGRepresentation(image) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"png"]] options:NSAtomicWrite error:nil];
    } else if ([[extension lowercaseString] isEqualToString:@"jpg"] || [[extension lowercaseString] isEqualToString:@"jpeg"]) {
        [UIImageJPEGRepresentation(image, 1.0) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"jpg"]] options:NSAtomicWrite error:nil];
    } else {
        NSLog(@"Image Save Failed\nExtension: (%@) is not recognized, use (PNG/JPG)", extension);
    }
}
-(UIImage *) loadImage:(NSString *)fileName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
    UIImage * result = [UIImage imageWithContentsOfFile:[NSString stringWithFormat:@"%@/%@.%@", directoryPath, fileName, extension]];

    return result;
}

下载图像，保存到文件并从文件加载成功地工作。但我希望得到我保存的所有图像文件。所以我不想指定图像名称。我怎么能这样做？

Answer 1

你必须知道你想要读什么。可能有很多方法 - 这里有两个：

存储每个文件的文件名并迭代这些文件名。
将图像存储在某个目录中并循环遍历目录内容。

Answer 2

当您保存图像时，请制定一些命名约定，即image01.png，image02.png，image03.png，这样当您加载它们时，您可以简单地遍历For循环并调用函数已写道：

for (int i = 1; i <= imagesCount; i++) {    
    NSString* twoDigitNumber;
    if (i < 10) {
        twoDigitNumber = [NSString stringWithFormat:@"0%d", i];
    }
    else {
        twoDigitNumber = [NSString stringWithFormat:@"%d", i];
    }

    NSString* imageName = [NSString stringWithFormat:@"image%@", twoDigitNumber];

    UIImage* image = [self loadImage:imageName inDirectory:......]; // Complete your code here
}

Objective-C从文件中获取所有图像

2 个答案: