iOS毛玻璃效果（不需要任何第三方的东东）

分享两种毛玻璃效果设置的方法，不需要任何三方东东，先看效果：

原图：

方法一（iOS8系统方法）：

方法二：

下面是示例代码：

#import "ViewController.h"

@interface ViewController ()
{
    UIImageView *_imageView;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    _imageView = [[UIImageView alloc]initWithFrame:self.view.bounds];
    _imageView.image = [UIImage imageNamed:@"1.jpg"];
    [self.view addSubview:_imageView];
    
    //方法一：系统方法，iOS8及以上可用
    if (!UIAccessibilityIsReduceTransparencyEnabled()) {
        UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];
        UIVisualEffectView *blurEffectView = [[UIVisualEffectView alloc]initWithEffect:blurEffect];
        blurEffectView.frame = _imageView.bounds;
        [_imageView addSubview:blurEffectView];
    }
    
    
    //方法二：Core Image
    UIImageView *blurImageView = [[UIImageView alloc]initWithFrame:_imageView.bounds];
    blurImageView.image = [self blur:[UIImage imageNamed:@"1.jpg"]];
    [_imageView addSubview:blurImageView];
}

//生成一张毛玻璃图片
- (UIImage*)blur:(UIImage*)theImage
{
    CIContext *context = [CIContext contextWithOptions:nil];
    CIImage *inputImage = [CIImage imageWithCGImage:theImage.CGImage];
    
    CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];
    [filter setValue:inputImage forKey:kCIInputImageKey];
    [filter setValue:[NSNumber numberWithFloat:15.0f] forKey:@"inputRadius"];
    CIImage *result = [filter valueForKey:kCIOutputImageKey];
    
    CGImageRef cgImage = [context createCGImage:result fromRect:[inputImage extent]];
    
    UIImage *returnImage = [UIImage imageWithCGImage:cgImage];
    CGImageRelease(cgImage);
    return returnImage;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

具体效果和参数自行研究吧！