ios8下添加高斯模糊、ios7创建快照

1.添加系统高斯模糊

UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"IMG_0004"]];
    imageView.frame = CGRectMake(0, 0,320, 720);
    [self.view addSubview:imageView];
    //ios8下添加高斯模糊，模糊有3种类型
    UIVisualEffectView *effectView = [[UIVisualEffectView alloc]initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleDark]];
    effectView.frame = CGRectMake(0, 100, 320, 100);
    [imageView addSubview:effectView];
    //
    UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];
    btn.frame = CGRectMake(10, 50, 100, 40);
    btn.backgroundColor = [UIColor cyanColor];
    [btn setTitle:@"btn" forState:UIControlStateNormal];
    [effectView.contentView addSubview:btn];

 2.添加定制高斯模糊

    //高斯模糊
    CIContext *context = [CIContext contextWithOptions:nil];
    CIImage *inputImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"56.jpg"]];
    // create gaussian blur filter
    CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];
    [filter setValue:inputImage forKey:kCIInputImageKey];
    [filter setValue:[NSNumber numberWithFloat:10.0] forKey:@"inputRadius"];
    // blur image
    CIImage *result = [filter valueForKey:kCIOutputImageKey];
    CGImageRef cgImage = [context createCGImage:result fromRect:[result extent]];
    UIImage *image = [UIImage imageWithCGImage:cgImage];
    CGImageRelease(cgImage);
    self.imageView.image = image;

3.创建快照

UIImageView    *showView         = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
    showView.image = [UIImage imageNamed:@"IMG_0003"];
    [self.view addSubview:showView];
    
    // 截取的view，设置NO透明度为0，Yes透明度为1
    UIView *snap1 = [showView snapshotViewAfterScreenUpdates:NO];
    snap1.center  = self.view.center;
    [self.view addSubview:snap1];
    NSLog(@"alpha=%f",snap1.alpha);