相关疑难解决方法(0)

如何清除UIImage的洋红色部分并使其透明？

我已经浏览了很多答案和SO上的链接,没有任何作用(例如,如何在UIImage上使一种颜色透明？答案1删除除红色之外的所有内容,答案2显然不起作用,因为为什么CGImageCreateWithMaskingColors()返回nil in这种情况？).

更新:

如果我使用CGImageCreateWithMaskingColors与UIImage我得到一个零值.如果我删除alpha通道(我将图像表示为JPEG并将其读回),CGImageCreateWithMaskingColors将返回涂有黑色背景的图像.

Update2,代码:

返回零:

const float colorMasking[6] = {222, 255, 222, 255, 222, 255};
CGImageRef imageRef = CGImageCreateWithMaskingColors(anchorWithMask.CGImage, colorMasking);

NSLog(@"image ref %@", imageRef);
// this is going to return a nil imgref.

UIImage *image = [UIImage imageWithCGImage:imageRef];

返回带有黑色背景的图像(这是正常的,因为没有alpha通道):

UIImage *inputImage = [UIImage imageWithData:UIImageJPEGRepresentation(anchorWithMask, 1.0)];

const float colorMasking[6] = {222, 255, 222, 255, 222, 255};
CGImageRef imageRef = CGImageCreateWithMaskingColors(inputImage.CGImage, colorMasking);

NSLog(@"image ref %@", imageRef);
// imgref is NOT nil.

UIImage *image = [UIImage imageWithCGImage:imageRef]; …

我有一种方法可以接收UIImage我将其转换为NSData并发出发布该数据的请求，它适用于 iOS 6，但是当我尝试使用 iOS 7 时，图像丢失了透明背景。

这是我迄今为止尝试过的：

-(void)post:(UIImage *)firm name:
{

    int x = 350;

    NSData *imageData = UIImagePNGRepresentation(firm);
    UIImage *image=[UIImage imageWithData:imageData];
    UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(10, x, 40, 50)];
    imageView.backgroundColor = [UIColor clearColor];
    imageView.image = image;


    NSData *imageData2 = [NSData dataWithData:UIImagePNGRepresentation(firm)];
    UIImage *image2=[UIImage imageWithData:imageData2];
    UIImageView *imageView2 = [[UIImageView alloc]initWithFrame:CGRectMake(160, x, 40, 50)];
    imageView2.image = image2;

    UIImageView *imageView3 = [[UIImageView alloc]initWithFrame:CGRectMake(110, x, 40, 50)];
    imageView3.image = firm;

    UIImage * img = [UIImage imageWithData:UIImagePNGRepresentation(image)];
    UIImageView *imageView4 = …