-[UIImage _imageByUnpremultiplying]：无法识别的选择器发送到实例答案

【问题标题】：-[UIImage _imageByUnpremultiplying]: unrecognized selector sent to instance-[UIImage _imageByUnpremultiplying]：无法识别的选择器发送到实例
【发布时间】：2014-03-24 01:53:44
【问题描述】：

我在使用 CI 过滤器并收到奇怪的错误，我如何通过查看日志来知道我缺少什么

CIFilter *filter = [CIFilter filterWithName:@"CIFalseColor"];        
    [filter setValue:image forKey:@"inputImage"];
    CIColor *myBlue = [CIColor colorWithRed:0.0 green:0.0 blue:0.6 alpha:0.5];
    [filter setValue:myBlue forKey:@"inputColor0"];
    CIImage *filteredImageData = [filter valueForKey:@"outputImage"];
    UIImage *newImage = [UIImage imageWithCIImage:filteredImageData];
     _imageView.image=newImage;



2014-02-22 16:04:12.002 colorMaker[1574:70b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIImage _imageByUnpremultiplying]: unrecognized selector sent to instance 0x8b7aca0'

libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

【问题讨论】：

看起来可能是一个 UIKit 错误。

标签： ios objective-c xcode uiimage cifilter

【解决方案1】：

如果您设置为"inputImage" 的对象是UIImage，则会发生此异常。根据documentation，inputImage 对象必须是CIImage。

尝试先从你的 UIImage 获取 CIImage。

[filter setValue:image.CIImage forKey:@"inputImage"];
                       ^^^^^^^

【讨论】：

【解决方案2】：

在马蒂亚的帮助下终于解决了。正确的代码是..

CIFilter *filter = [CIFilter filterWithName:@"CIFalseColor"];        
CIImage *  beginImage = [CIImage imageWithCGImage:image.CGImage];
// set value must be of ciimage not uiimage
[filter setValue:beginImage forKey:@"inputImage"];
CIColor *myBlue = [CIColor colorWithRed:0.0 green:0.0 blue:0.6 alpha:0.5];
[filter setValue:myBlue forKey:@"inputColor0"];
CIImage *filteredImageData = [filter valueForKey:@"outputImage"];
UIImage *newImage = [UIImage imageWithCIImage:filteredImageData];
_imageView.image=newImage;

【讨论】：