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;