+ (UIImage *)blurWithCoreImage:(UIImage *)sourceImage withFrame:(CGRect)frame
{
CIImage *inputImage = [CIImage imageWithCGImage:sourceImage.CGImage];
// Apply Affine-Clamp filter to stretch the image so that it does not look shrunken when gaussian blur is applied
CGAffineTransform transform = CGAffineTransformIdentity;
CIFilter *clampFilter = [CIFilter filterWithName:@"CIAffineClamp"];
[clampFilter setValue:inputImage forKey:@"inputImage"];
[clampFilter setValue:[NSValue valueWithBytes:&transform objCType:@encode(CGAffineTransform)] forKey:@"inputTransform"];
// Apply gaussian blur filter with radius of 30
CIFilter *gaussianBlurFilter = [CIFilter filterWithName: @"CIGaussianBlur"];
[gaussianBlurFilter setValue:clampFilter.outputImage forKey: @"inputImage"];
[gaussianBlurFilter setValue:@3 forKey:@"inputRadius"];
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef cgImage = [context createCGImage:gaussianBlurFilter.outputImage fromRect:[inputImage extent]];
// Set up output context.
UIGraphicsBeginImageContext(frame.size);
CGContextRef outputContext = UIGraphicsGetCurrentContext();
CGContextScaleCTM(outputContext, 1.0, -1.0);
CGContextTranslateCTM(outputContext, 0, - frame.size.height);
// Draw base image.
CGContextDrawImage(outputContext, frame, cgImage);
// Apply white tint
CGContextSaveGState(outputContext);
CGContextSetFillColorWithColor(outputContext, [UIColor colorWithWhite:1 alpha:0.2].CGColor);
CGContextFillRect(outputContext, frame);
CGContextRestoreGState(outputContext);
// Output image is ready.
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
CGImageRelease(cgImage);
UIGraphicsEndImageContext();
return outputImage;
}
原文：http://www.cnblogs.com/417460188dy/p/4580925.html