iOS 图片背景模糊效果

1.使用CoreImage中的模糊滤镜

原始效果图例如以下:

CoreImage的实现:

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    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];

    //用来查询滤镜能够设置的參数以及一些相关的信息
    NSLog(@"%@",[blurFilter attributes]);

    //设置模糊程度,默觉得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]];

    //终于获取到图片
    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]打印结果例如以下:
//參数以及一些相关的信息,假设不做不论什么的设置,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效果图例如以下:

默认程度为50效果图例如以下:

2.使用UIImage+ImageEffects

到该地址下载:https://github.com/YouXianMing/UIImageBlur,里面还有非常多好东西,值得关注;
导入UIImage+ImageEffects文件到project中就可以使用;

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];

    /*其它的一些方法,能够自己尝试使用
     //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];

效果图分别例如以下:

//局部模糊

//灰色

3.使用UIVisualEffectView

注意:UIVisualEffectView仅仅适用用户iOS 8或以上,才干够使用8下面则不能使用;

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];

    //加入显示文本
    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];

效果图例如以下:

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];

    //加入显示文本
    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加入到effectView的contentView才干够生效
    [effectView.contentView addSubview:subEffectView];

    //4.加入要显示的view来达到特殊的效果
    [subEffectView.contentView addSubview:lable];

效果图例如以下:

4.下载图片后自己主动模糊效果

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;

//開始运行
- (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]];

            //由于是同步请求,会堵塞主线程(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,会堵塞主线程(mainQueue)
            UIImage * blurImage = [image blurImage];

            [GCDQueue executeInMainQueue:^{
                //载入图片
                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];
}

效果图例如以下: