ios开发中常常用到的毛玻璃效果实现方法

iOS8以后使用系统里的UIBlurEffect可以实现,UIBlurEffect继承自UIVisualEffect

UIBlurEffectStyle有三个值,UIBlurEffectStyleLight , UIBlurEffectStyleExtraLight , UIBlurEffectStyleDark,可以控制毛玻璃的效果.

    UIBlurEffect *effect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];

    UIVisualEffectView *effectView = [[UIVisualEffectView alloc] initWithEffect:effect];

//必须给effcetView的frame赋值,因为UIVisualEffectView是一个加到UIIamgeView上的子视图.

    effectView.frame = _imageView.bounds;

    [self.imageView addSubview:effectView];

UIVibrancyEffect也继承自UIVisualEffect类,可以用来设置一些特殊的效果.代码如下

    UIBlurEffect *effect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];

    UIVisualEffectView *effectView = [[UIVisualEffectView alloc] initWithEffect:effect];

    effectView.frame = _imageView.bounds;

    UIVibrancyEffect *viBrancyeffect = [UIVibrancyEffect effectForBlurEffect:effect];

    UIVisualEffectView *vibrancyEffectView = [[UIVisualEffectView alloc] initWithEffect:viBrancyeffect];

    vibrancyEffectView.frame = CGRectMake(100, 0, 200, 200);

    UILabel *lbl = [[UILabel alloc] init];

    lbl.text = @"测试Label";

    lbl.font = [UIFont systemFontOfSize:25];

    lbl.frame = CGRectMake(0, 0, 200, 200);

    [vibrancyEffectView.contentView addSubview:lbl];

    [effectView.contentView addSubview:vibrancyEffectView];

    [self.imageView addSubview:effectView];

但是这种毛玻璃效果不能很好的控制模糊效果,可以alpha属性控制并不完美.
效果如下:

使用系统CoreImage中的滤镜产生毛玻璃效果

原理是给图片添加滤镜,这种方式相比上面更为可控,下面介绍一下系统滤镜中支持的毛玻璃效果

先简要介绍一下系统滤镜CIFilter的使用

CIfilter中有一个专门用于毛玻璃效果的Category : kCICategoryBlur
使用下面的代码可以打印出这个分类下的滤镜

NSArray *filters = [CIFilter filterNamesInCategory:kCICategoryBlur];

可以得到结果

**    CIBoxBlur,**

**    CIDiscBlur,**

**    CIGaussianBlur,**

**    CIMaskedVariableBlur,**

**    CIMedianFilter,**

**    CIMotionBlur,**

**    CINoiseReduction,**

**    CIZoomBlur**

我们使用最常见的高斯模糊 (Gaussian Blur) 来进行举例

NSArray *inputKeys = filter.inputKeys;

可以得到这个滤镜支持两个输入属性,分别是inputImage,inputRadius
其中inputImage指你需要添加滤镜效果的图片,inputRadius指进行高斯模糊的程度
设置属性的方式有两种
一种是直接通过NSDictionary赋值

CIImage *testCIImage = [CIImage imageWithCGImage:[UIImage imageNamed:@"testImg.jpg"].CGImage];

    NSDictionary *filterAttDict = @{@"inputImage" : testCIImage

                                    ,@"inputRadius" : [NSNumber numberWithDouble:5.0f]};

    CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur" withInputParameters:filterAttDict];

CIImage *outPutCIImage = [filter outputImage];

CIContext *ciContext = [CIContext contextWithOptions:nil];

    CGImageRef cgImage = [ciContext createCGImage:outPutCIImage fromRect:outPutCIImage.extent];

    UIImage *resImage = [UIImage imageWithCGImage:cgImage];

另一种是通过kvc方法赋值

    CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];

    CIImage *testCIImage = [CIImage imageWithCGImage:[UIImage imageNamed:@"testImg.jpg"].CGImage];

    [filter setValue:testCIImage forKeyPath:kCIInputImageKey];

    [filter setValue:@50 forKeyPath:kCIInputRadiusKey];

    CIImage *outPutCIImage = [filter outputImage];

    CIContext *ciContext = [CIContext contextWithOptions:nil];

    CGImageRef cgImage = [ciContext createCGImage:outPutCIImage fromRect:outPutCIImage.extent];

    UIImage *resImage = [UIImage imageWithCGImage:cgImage];

发现一个写的比较详细的博客,可以参考 http://www.jianshu.com/p/d115836ed3fa