iOS 滤镜 转载，原文见正文首行链接

转载自：http://blog.sina.com.cn/s/blog_5fb39f9101018gv7.html

直接上代码了：

//
//  ViewController.m
//  图片模糊处理
//
//  Created by wusiping on 16/1/28.
//  Copyright © 2016年 wusiping. All rights reserved.
//

#import "ViewController.h"
#import <AssetsLibrary/AssetsLibrary.h>

@interface ViewController ()<UINavigationControllerDelegate,UIImagePickerControllerDelegate>

@end

@implementation ViewController{
    CIContext *context;
    CIFilter *filter;
    CIImage *beginImage;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    //取得图片路径
    NSString *filePath = [[NSBundle mainBundle] pathForResource:@"image" ofType:@"png"];
    NSURL *fileNameAndPath = [NSURL fileURLWithPath:filePath];
    //根据路径，创建开始图片
    beginImage = [CIImage imageWithContentsOfURL:fileNameAndPath];

    context = [CIContext contextWithOptions:nil];
    //创建滤镜，和输出图片
    filter = [CIFilter filterWithName:@"CISepiaTone" keysAndValues: kCIInputImageKey, beginImage, @"inputIntensity", @0.8, nil];
    CIImage *outputImage = [filter outputImage];

    //在这里你用上下文对象里的一个方法来画一个CGImage,调用上下文中的createCGImage:fromRect:和提供的CIImage可以生成一个CGImageRef。
    CGImageRef cgimg = [context createCGImage:outputImage fromRect:[outputImage extent]];

    //下面，你用UIImage + imageWithCGImage，从CGImage中创建一个UIImage。
    UIImage *newImage = [UIImage imageWithCGImage:cgimg];
    self.imageView.image = newImage;

    //最后，开放 CGImageRef接口。 CGImage 是一个C接口，即使有ARC，也需要你自己来做内存管理。编译运行，确保正常工作。
    CGImageRelease(cgimg);

    [self logAllFilters];
 }

- (IBAction)amountSliderValueChanged:(id)sender {
    float slideValue = self.amountSlider.value;
    [filter setValue:@(slideValue) forKey:@"inputIntensity"];
    CIImage *outputImage = [filter outputImage];
    CGImageRef cgimg = [context createCGImage:outputImage fromRect:[outputImage extent]];
    UIImage *newImage = [UIImage imageWithCGImage:cgimg];
    self.imageView.image = newImage;
    CGImageRelease(cgimg);
}

- (IBAction)loadPhoto:(id)sender {
    UIImagePickerController *pickerC = [[UIImagePickerController alloc] init];
    pickerC.delegate = self;
    [self presentViewController:pickerC animated:YES completion:nil];
}

- (IBAction)savePhoto:(id)sender {
    CIImage *saveToSave = [filter outputImage];
    CIContext *softwareContext = [CIContext contextWithOptions:@{kCIContextUseSoftwareRenderer : @(YES)} ];
    CGImageRef cgImg = [softwareContext createCGImage:saveToSave fromRect:[saveToSave extent]];
    ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
    [library writeImageToSavedPhotosAlbum:cgImg metadata:[saveToSave properties] completionBlock:^(NSURL *assetURL, NSError *error) { CGImageRelease(cgImg); }];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    [self dismissViewControllerAnimated:YES completion:nil];
    UIImage *gotImage = [info objectForKey:UIImagePickerControllerOriginalImage];
    beginImage = [CIImage imageWithCGImage:gotImage.CGImage];
    [filter setValue:beginImage forKey:kCIInputImageKey];
    [self amountSliderValueChanged:self.amountSlider];
}

- (void)imagePickerControllerDidCancel: (UIImagePickerController *)picker {
    [self dismissViewControllerAnimated:YES completion:nil];
}

/**
 *  打印所有滤镜
 */
-(void)logAllFilters {
    NSArray *properties = [CIFilter filterNamesInCategory: kCICategoryBuiltIn];
    NSLog(@"%@", properties);
    for (NSString *filterName in properties){
        CIFilter *fltr = [CIFilter filterWithName:filterName];
        NSLog(@"%@", [fltr attributes]);
    }
}

@end