1.使用CoreImage中的模糊滤镜原始效果图如下: 这里写图片描述 CoreImage的实现:

- (void)viewDidLoad { 
[super viewDidLoad]; 
UIImage * image = [UIImage imageNamed:@"icon"]; 
 /*..CoreImage中的模糊效果滤镜..*/ 
 //CIImage,相当于UIImage,作用为获取图片资源 
CIImage * ciImage = [[CIImage alloc]initWithImage:image ]; 
//CIFilter,高斯模糊滤镜
 CIFilter * blurFilter = [CIFilter filterWithName:@"CIGaussianBlur"]; 
 //将图片输入到滤镜中 
[blurFilter setValue:ciImage forKey:kCIInputImageKey];  
//用来查询滤镜可以设置的参数以及一些相关的信息 
NSLog(@"%@",[blurFilter attributes]);  
//设置模糊程度,默认为10,取值范围(0-100) 
[blurFilter setValue:@(20) forKey:@"inputRadius"];  
//将处理好的图片输出
 CIImage * outCiImage = [blurFilter valueForKey:kCIOutputImageKey];  
//CIContext 
CIContext * context = [CIContext contextWithOptions:nil];  
//获取CGImage句柄,也就是从数据流中取出图片
 CGImageRef outCGImage = [context createCGImage:outCiImage fromRect:[outCiImage extent]];  
//最终获取到图片
 UIImage * blurImage = [UIImage imageWithCGImage:outCGImage];  
//释放CGImage句柄 
CGImageRelease(outCGImage); 
 UIImageView * imageView = [[UIImageView alloc]initWithFrame:self.view.bounds]; imageView.image = blurImage; [self.view addSubview:imageView];
}

[blurFilter attributes]打印结果如下:
//参数以及一些相关的信息,如果不做任何的设置,默认程度为10( CIAttributeDefault = 10);
{ 
"CIAttributeFilterAvailable_Mac" = "10.4"; 
"CIAttributeFilterAvailable_iOS" = 6; 
CIAttributeFilterCategories = ( CICategoryBlur, CICategoryStillImage, CICategoryVideo, CICategoryBuiltIn ); 
CIAttributeFilterDisplayName = "Gaussian Blur"; 
CIAttributeFilterName = CIGaussianBlur; 
CIAttributeReferenceDocumentation = "http://developer.apple.com/cgi-bin/apple_ref.cgi?apple_ref=//apple_ref/doc/filter/ci/CIGaussianBlur";
 inputImage = { 
CIAttributeClass = CIImage;
 CIAttributeDescription = "The image to use as an input image. For filters that also use a background image, this is the foreground image.";
 CIAttributeDisplayName = Image;
 CIAttributeType = CIAttributeTypeImage; 
};
 inputRadius = {
 CIAttributeClass = NSNumber;
 CIAttributeDefault = 10;
 CIAttributeDescription = "The radius determines how many pixels are used to create the blur. The larger the radius, the blurrier the result."; 
CIAttributeDisplayName = Radius; 
CIAttributeIdentity = 0; 
CIAttributeMin = 0; 
CIAttributeSliderMax = 100;
 CIAttributeSliderMin = 0;
 CIAttributeType = CIAttributeTypeScalar; 
};
}```
默认程度为10效果图如下:![这里写图片描述](http:https://img.haomeiwen.com/i1485325/cc76711e082f0adf?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240) 默认程度为50效果图如下:![这里写图片描述](https://img.haomeiwen.com/i1485325/d7bb4a6c24460d6b?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

 #### 2.使用UIImage+ImageEffects
到该地址下载:https://github.com/YouXianMing/UIImageBlur,里面还有很多好东西,值得关注;
导入UIImage+ImageEffects文件到工程中即可使用;
UIImage+ImageEffects的实现:

UIImage * image = [UIImage imageNamed:@"icon"];
//模糊效果渲染耗费时间,建议在子线程中渲染
//对图片进行模糊
UIImage * blurImage = [image blurImage];
//设置模糊度
UIImage * blurImage1 = [image blurImageWithRadius:10];
//设置局部模糊度
UIImage * blurImage2 = [image blurImageAtFrame:CGRectMake(0, 0, image.size.width, image.size.height/2)];
//灰度效果
UIImage * blurImage3 = [image grayScale];
/*其他的一些方法,可以自己尝试使用
//固定宽度与固定高度

• (UIImage *)scaleWithFixedWidth:(CGFloat)width;
• (UIImage *)scaleWithFixedHeight:(CGFloat)height;
  //平均的颜色
• (UIColor *)averageColor;
  //裁剪图片的一部分
• (UIImage *)croppedImageAtFrame:(CGRect)frame;
  */
  UIImageView * imageView = [[UIImageView alloc]initWithFrame:self.view.bounds]; imageView.image = blurImage; [self.view addSubview:imageView];

效果图分别如下:![这里写图片描述](http:https://img.haomeiwen.com/i1485325/b12d3ce7472c76ac?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240) 
//局部模糊![这里写图片描述](https://img.haomeiwen.com/i1485325/93df8f7fcf05914d?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
//灰色![这里写图片描述](http:https://img.haomeiwen.com/i1485325/a451ee652ba02b89?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

#### 3.使用UIVisualEffectView
注意:UIVisualEffectView只适用用户iOS 8或以上,才可以使用8以下则不能使用;
UIVisualEffectView的实现:
1.直接将文本内容加在effectView(该情况下的文本内容不能与背景相符应);

UIImage * image = [UIImage imageNamed:@"icon"];
UIImageView * imageView = [[UIImageView alloc]initWithFrame:self.view.bounds]; imageView.image = image;
[self.view addSubview:imageView];
UIBlurEffect * blur = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
//创建模糊view
UIVisualEffectView * effectView = [[UIVisualEffectView alloc]initWithEffect:blur];
effectView.frame = CGRectMake(0, 250, imageView.frame.size.width, 200);
[imageView addSubview:effectView];
//添加显示文本
UILabel * lable = [[UILabel alloc]initWithFrame:effectView.bounds];
lable.text = @"哈哈哈哈哈";
lable.textAlignment = NSTextAlignmentCenter;
lable.font = [UIFont systemFontOfSize:24];
[effectView.contentView addSubview:lable];

效果图如下:![这里写图片描述](http:https://img.haomeiwen.com/i1485325/54bee101c7ac7010?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
 2.加在effectView的子view中使文本与背景相符应;

UIImage * image = [UIImage imageNamed:@"icon"];
UIImageView * imageView = [[UIImageView alloc]initWithFrame:self.view.bounds]; imageView.image = image; [self.view addSubview:imageView];
UIBlurEffect * blur = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
//创建模糊view
UIVisualEffectView * effectView = [[UIVisualEffectView alloc]initWithEffect:blur];
effectView.frame = CGRectMake(0, 250, imageView.frame.size.width, 200);
[imageView addSubview:effectView];
//添加显示文本
UILabel * lable = [[UILabel alloc]initWithFrame:effectView.bounds];
lable.text = @"哈哈哈哈哈";
lable.textAlignment = NSTextAlignmentCenter;
lable.font = [UIFont systemFontOfSize:24];
//创建模糊子view的UIVisualEffectView
//1.创建出子模糊view
UIVisualEffectView * subEffectView = [[UIVisualEffectView alloc]initWithEffect:[UIVibrancyEffect effectForBlurEffect:(UIBlurEffect *)effectView.effect]];
//2.设定尺寸
subEffectView.frame = effectView.bounds;
//3.将子模糊view添加到effectView的contentView才能够生效
[effectView.contentView addSubview:subEffectView];
//4.添加要显示的view来达到特殊的效果
[subEffectView.contentView addSubview:lable];

效果图如下:![这里写图片描述](http:https://img.haomeiwen.com/i1485325/f6f2a722e7e51bc4?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
 #### 4.下载图片后自动模糊效果
在项目中导入UIImage+ImageEffects和GCD文件;
UIImage+ImageEffects地址:https://github.com/YouXianMing/UIImageBlur;
GCD地址:https://github.com/YouXianMing/GCD-Program;
代码的实现:
创建一个UIView的子类,命名为BlurDownloadPicView;
BlurDownloadPicView.h的里面内容:

import <UIKit/UIKit.h>@interface BlurDownloadPicView : UIView

//图片下载地址
@property (nonatomic, strong)NSString * picUrl;
//图片显示的方式
@property (nonatomic)UIViewContentMode contentMode;
//开始执行

• (void)startProgress;
  @end

BlurDownloadPicView.m的里面内容:

import "BlurDownloadPicView.h"

import "GCD.h"

import "UIImage+ImageEffects.h"

@interface BlurDownloadPicView ()
@property (nonatomic, strong)UIImageView * imageView;
@end
@implementation BlurDownloadPicView

• (instancetype)initWithFrame:(CGRect)frame{
  self = [super initWithFrame:frame];
  if (self) {
  [self loadSubViews];
  }
  return self;
  }
• (void)loadSubViews{
  self.imageView = [[UIImageView alloc]initWithFrame:self.bounds];
  self.imageView.alpha = 0;
  [self addSubview:self.imageView];
  }
• (void)startProgress{
  if (self.picUrl) {
  [GCDQueue executeInGlobalQueue:^{
  //创建请求
  NSURLRequest * request = [NSURLRequest requestWithURL:[NSURL URLWithString:self.picUrl]]; //因为是同步请求,会阻塞主线程(mainQueue)
  NSData * data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
  //获取图片
  UIImage * image = [[UIImage alloc]initWithData:data];
  //对图片进行模糊,会阻塞主线程(mainQueue)
  UIImage * blurImage = [image blurImage];
  [GCDQueue executeInMainQueue:^{
  //加载图片
  self.imageView.image = blurImage;
  [UIView animateWithDuration:1 animations:^{
  self.imageView.alpha = 1;
  }];
  }];
  }];
  }
  }
  //重写set,get方法
  -(void)setContentMode:(UIViewContentMode)contentMode{
  self.contentMode = contentMode;
  self.imageView.contentMode = contentMode;
  }
• (UIViewContentMode)contentMode{
  return self.contentMode;}

在ViewController.m里面的实现;
引入#import "BlurDownloadPicView.h"头文件

在viewDidLoad里面的代码实现

• (void)viewDidLoad {
  [super viewDidLoad];
  NSString * picUrl = @"http://i4.download.fd.pchome.net/g1/M00/0D/1C/oYYBAFTEeAmIWRXgAAKhY5iKdP8AACP_QP4y0IAAqF7878.jpg";
  BlurDownloadPicView * blurPicView = [[BlurDownloadPicView alloc]initWithFrame:self.view.bounds];
  [self.view addSubview:blurPicView];
  blurPicView.picUrl = picUrl;
  [blurPicView startProgress];
  }

效果图如下:![这里写图片描述](https://img.haomeiwen.com/i1485325/6d0fc61a9677e700?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)