ios - 使用图像自定义进度条

Question

我正在开发一个自定义进度条，它将根据百分比值显示图像的一部分。我的想法是有两张图片，原版和黑白版。我正在显示黑白图像，最重要的是我正在根据百分比裁剪原始图像。从上到下运行良好。

请问，有什么办法可以让原图从下往上“长”？

以下是到目前为止我的代码示例:

    UIImageView *imgDefViewGray = [[UIImageView alloc] initWithFrame:CGRectMake(170, 85, 60, 60)];
    imgDefViewGray.image = [UIImage imageNamed:@"castle-gray.png"];
    [self addSubview:imgDefViewGray];

    UIImageView *imgDefView = [[UIImageView alloc] initWithFrame:CGRectMake(170, 85, 60, 60)];
    imgDefView.image = [UIImage imageNamed:@"castle.png"];

    CGRect rect = CGRectMake(0, 0 , 60, **50**);
    CGImageRef imageRef = CGImageCreateWithImageInRect([imgDefView.image CGImage], rect);
    UIImage *img = [UIImage imageWithCGImage:imageRef];

    imgDefView = [[UIImageView alloc] initWithFrame:CGRectMake(170, 85, 60, **50**)];
    imgDefView.image = img;
    [self addSubview:imgDefView];

因此，通过更改 Bold(双星号)的值，我已经实现了按我想要的方式裁剪原始图像，但方向为 top->bottom。我想要底部->顶部。

提前致谢

Answer 1

经过多次尝试，我找到了想要的结果。以下是我对我的问题的解决方案。我希望将来遇到或想要同样的人发现它有用。

    UIImageView *imgDefViewGray = [[UIImageView alloc] initWithFrame:CGRectMake(170, 85, 60, 60)];
    imgDefViewGray.image = [UIImage imageNamed:@"castle-gray.png"];//60x60 b&w image

    UIImage originalImg = [UIImage imageNamed:@"castle.png"];//60x60 original image
    CGRect rect = CGRectMake(0, originalImg.size.height-scaleDefence), 60 , scaleDefence);//scaleDefence is just a float variable that converts current percentage value to px.

    CGImageRef imageRef = CGImageCreateWithImageInRect([originalImg CGImage], rect);
    UIImage *croppedImg = [UIImage imageWithCGImage:imageRef];

    UIImageView *imgDefView = [[UIImageView alloc] initWithFrame:CGRectMake(0, originalImg.size.height-scaleDefence, 60, scaleDefence)];//dynamically changing y-axis depending on cropped image's height.
    imgDefView.image = croppedImg;

    [imgDefViewGray addSubview:imgDefView];//make original image part of b&w
    [self addSubview:imgDefViewGray];//finally add the result to the view