Xcode9学习笔记55 - 使用CoreImage框架设置图片的单色效果

import UIKit
//导入CoreImage框架，该框架提供了强大和高效的图像处理功能，用来对基于像素的图像进行分析、操作和特效处理
import CoreImage

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        
        let image = UIImage(named: "Pic1")
        let imageView = UIImageView(image: image)
        self.view.addSubview(imageView)
        
        let ciImage = CIImage(image: image!)//初始化一个图像对象，并加载之前导入的图片
        //初始化一个颜色对象，并设置其颜色值为棕色，其参数值介于0和1之间
        let color = CIColor(red: 0.8, green: 0.6, blue: 0.4)
        let filter = CIFilter(name: "CIColorMonochrome")//初始化一个滤镜对象，并设置滤镜类型为单色调滤镜
        filter?.setValue(color, forKey: kCIInputColorKey)//设置单色调滤镜的输入颜色值
        filter?.setValue(1.0, forKey: kCIInputIntensityKey)//设置单色调滤镜的颜色浓度值
        filter?.setValue(ciImage, forKey: kCIInputImageKey)//设置需要应用单色调滤镜的图像
        let outImage = filter?.outputImage//获得应用单色调滤镜后的图像
        
        imageView.image = UIImage(ciImage: outImage!)//ciImage，前2个字符要小写
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}