背景虚化

CIContext *context = [CIContext contextWithOptions:nil];
CIImage *inputImage = [CIImage imageWithContentsOfURL:[NSURL URLWithString:str]];

CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];

[filter setValue:inputImage forKey:kCIInputImageKey];

[filter setValue:[NSNumber numberWithFloat:3.0] forKey:@"inputRadius"];

CIImage *result=[filter outputImage];

CGImageRef cgImage = [context createCGImage:result fromRect:[inputImage extent]];

UIImage *image = [UIImage imageWithCGImage:cgImage];

CGImageRelease(cgImage);
self.Image.image = image;