1.使用CoreImage中的模糊濾鏡原始效果圖如下:

這里寫圖片描述

CoreImage的實現:

- (void)viewDidLoad { 
[super viewDidLoad]; 
UIImage * image = [UIImage imageNamed:@"icon"]; 
 /*..CoreImage中的模糊效果濾鏡..*/ 
 //CIImage,相當于UIImage,作用為獲取圖片資源 
CIImage * ciImage = [[CIImage alloc]initWithImage:image ]; 
//CIFilter,高斯模糊濾鏡
 CIFilter * blurFilter = [CIFilter filterWithName:@"CIGaussianBlur"]; 
 //將圖片輸入到濾鏡中 
[blurFilter setValue:ciImage forKey:kCIInputImageKey];  
//用來查詢濾鏡可以設置的參數以及一些相關的信息 
NSLog(@"%@",[blurFilter attributes]);  
//設置模糊程度,默認為10,取值范圍(0-100) 
[blurFilter setValue:@(20) forKey:@"inputRadius"];  
//將處理好的圖片輸出
 CIImage * outCiImage = [blurFilter valueForKey:kCIOutputImageKey];  
//CIContext 
CIContext * context = [CIContext contextWithOptions:nil];  
//獲取CGImage句柄,也就是從數據流中取出圖片
 CGImageRef outCGImage = [context createCGImage:outCiImage fromRect:[outCiImage extent]];  
//最終獲取到圖片
 UIImage * blurImage = [UIImage imageWithCGImage:outCGImage];  
//釋放CGImage句柄 
CGImageRelease(outCGImage); 
 UIImageView * imageView = [[UIImageView alloc]initWithFrame:self.view.bounds]; imageView.image = blurImage; [self.view addSubview:imageView];
}

[blurFilter attributes]打印結果如下:
//參數以及一些相關的信息,如果不做任何的設置,默認程度為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; 
};
}```
默認程度為10效果圖如下:![這里寫圖片描述](http://upload-images.jianshu.io/upload_images/1485325-cc76711e082f0adf?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240) 默認程度為50效果圖如下:![這里寫圖片描述](http://upload-images.jianshu.io/upload_images/1485325-d7bb4a6c24460d6b?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

 #### 2.使用UIImage+ImageEffects
到該地址下載:https://github.com/YouXianMing/UIImageBlur,里面還有很多好東西,值得關注;
導入UIImage+ImageEffects文件到工程中即可使用;
UIImage+ImageEffects的實現:

UIImage * image = [UIImage imageNamed:@"icon"];
//模糊效果渲染耗費時間,建議在子線程中渲染
//對圖片進行模糊
UIImage * blurImage = [image blurImage];
//設置模糊度
UIImage * blurImage1 = [image blurImageWithRadius:10];
//設置局部模糊度
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,可以自己嘗試使用
//固定寬度與固定高度

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

效果圖分別如下:![這里寫圖片描述](http://upload-images.jianshu.io/upload_images/1485325-b12d3ce7472c76ac?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240) 
//局部模糊![這里寫圖片描述](http://upload-images.jianshu.io/upload_images/1485325-93df8f7fcf05914d?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
//灰色![這里寫圖片描述](http://upload-images.jianshu.io/upload_images/1485325-a451ee652ba02b89?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

#### 3.使用UIVisualEffectView
注意:UIVisualEffectView只適用用戶iOS 8或以上,才可以使用8以下則不能使用;
UIVisualEffectView的實現:
1.直接將文本內容加在effectView(該情況下的文本內容不能與背景相符應);

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];
//創建模糊view
UIVisualEffectView * effectView = [[UIVisualEffectView alloc]initWithEffect:blur];
effectView.frame = CGRectMake(0, 250, imageView.frame.size.width, 200);
[imageView addSubview:effectView];
//添加顯示文本
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];

效果圖如下:![這里寫圖片描述](http://upload-images.jianshu.io/upload_images/1485325-54bee101c7ac7010?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
 2.加在effectView的子view中使文本與背景相符應;

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];
//創建模糊view
UIVisualEffectView * effectView = [[UIVisualEffectView alloc]initWithEffect:blur];
effectView.frame = CGRectMake(0, 250, imageView.frame.size.width, 200);
[imageView addSubview:effectView];
//添加顯示文本
UILabel * lable = [[UILabel alloc]initWithFrame:effectView.bounds];
lable.text = @"哈哈哈哈哈";
lable.textAlignment = NSTextAlignmentCenter;
lable.font = [UIFont systemFontOfSize:24];
//創建模糊子view的UIVisualEffectView
//1.創建出子模糊view
UIVisualEffectView * subEffectView = [[UIVisualEffectView alloc]initWithEffect:[UIVibrancyEffect effectForBlurEffect:(UIBlurEffect *)effectView.effect]];
//2.設定尺寸
subEffectView.frame = effectView.bounds;
//3.將子模糊view添加到effectView的contentView才能夠生效
[effectView.contentView addSubview:subEffectView];
//4.添加要顯示的view來達到特殊的效果
[subEffectView.contentView addSubview:lable];

效果圖如下:![這里寫圖片描述](http://upload-images.jianshu.io/upload_images/1485325-f6f2a722e7e51bc4?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
 #### 4.下載圖片后自動模糊效果
在項目中導入UIImage+ImageEffects和GCD文件;
UIImage+ImageEffects地址:https://github.com/YouXianMing/UIImageBlur;
GCD地址:https://github.com/YouXianMing/GCD-Program;
代碼的實現:
創建一個UIView的子類,命名為BlurDownloadPicView;
BlurDownloadPicView.h的里面內容:

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

//圖片下載地址
@property (nonatomic, strong)NSString * picUrl;
//圖片顯示的方式
@property (nonatomic)UIViewContentMode contentMode;
//開始執行

• (void)startProgress;
  @end

BlurDownloadPicView.m的里面內容:

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:^{
  //創建請求
  NSURLRequest * request = [NSURLRequest requestWithURL:[NSURL URLWithString:self.picUrl]]; //因為是同步請求,會阻塞主線程(mainQueue)
  NSData * data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
  //獲取圖片
  UIImage * image = [[UIImage alloc]initWithData:data];
  //對圖片進行模糊,會阻塞主線程(mainQueue)
  UIImage * blurImage = [image blurImage];
  [GCDQueue executeInMainQueue:^{
  //加載圖片
  self.imageView.image = blurImage;
  [UIView animateWithDuration:1 animations:^{
  self.imageView.alpha = 1;
  }];
  }];
  }];
  }
  }
  //重寫set,get方法
  -(void)setContentMode:(UIViewContentMode)contentMode{
  self.contentMode = contentMode;
  self.imageView.contentMode = contentMode;
  }
• (UIViewContentMode)contentMode{
  return self.contentMode;}

在ViewController.m里面的實現;
引入#import "BlurDownloadPicView.h"頭文件

在viewDidLoad里面的代碼實現

• (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];
  }

效果圖如下:![這里寫圖片描述](http://upload-images.jianshu.io/upload_images/1485325-6d0fc61a9677e700?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)