ios - NSDocumentDirectory 在设备上保存和加载图像是否合法？

Question

以下代码在模拟器上运行，但由于 img 为 nil 导致设备崩溃：

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];

    for (NSString* path in userImages) {
        NSLog(@"image at %@", path); //logs "image at userImage0.png"
        NSString *getImagePath = [documentsDirectory stringByAppendingPathComponent:path];
        UIImage *img = [UIImage imageWithContentsOfFile:getImagePath];
        unichar ch = [path characterAtIndex:9];
        NSLog(@"Ch = %c", ch); //correctly logs "0"
        if (ch == '0') {
            [self.images insertObject:img atIndex:0]; //this throws the error
        }
    }

为什么在设备上运行而不是在模拟器上运行时 img nil？图像最初是这样保存的：

NSString *docsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES) objectAtIndex:0];
NSString *imageName = @"userimage0.png";
NSString *imagePath = [docsDir stringByAppendingPathComponent:imageName];
[UIImagePNGRepresentation(img) writeToFile:imagePath atomically:YES];

Answer 1

对不起，这是一个大小写问题。用户图像与用户图像。模拟器不关心这个（我希望它这样做），但设备关心。