方案一:利用系統的CoreImage(濾鏡)

• 重點理解CIImage,CIFilter,CIContext,CGImageRef

• 濾鏡處理的過程比較慢,會造成加載圖片緩慢的現象(等一會才看到圖片),盡量放到子線程執行

- (void)viewDidLoad {
    [super viewDidLoad];

    // 加載一張圖片
    UIImage *image = [UIImage imageNamed:@"che"];
  
    /**************CoreImage部分**************/
    
    // 1.創建CIImage
    CIImage *ciImage = [[CIImage alloc] initWithImage:image];
    
    // 2.創建濾鏡CIFilter
    CIFilter *blurFilter = [CIFilter filterWithName:@"CIGaussianBlur"];
    
    // 2.1.將CIImage輸入到濾鏡中
    [blurFilter setValue:ciImage forKey:kCIInputImageKey];
    
    // 可以通過該方法查看我們可以設置的值(如模糊度等)
    NSLog(@"%@", [blurFilter attributes]);
    
    // 2.2設置模糊度
    [blurFilter setValue:@(2) forKey:@"inputRadius"];

    // 2.3將處理好的圖片輸出
    CIImage *outCiImage = [blurFilter valueForKey:kCIOutputImageKey];

    // 3.CIContext(option參數為nil代表用CPU渲染,若想用GPU渲染請查看此參數)
    CIContext *context = [CIContext contextWithOptions:nil];
    
    // 4.獲取CGImage句柄
    CGImageRef outCGImage = [context createCGImage:outCiImage fromRect:[outCiImage extent]];
    
    // 5.獲取最終的圖片
    UIImage *blurImage = [UIImage imageWithCGImage:outCGImage];
    
    // 6.釋放CGImage
    CGImageRelease(outCGImage);
    /*****************************************/
    
    UIImageView *imageV = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 750 / 2, 1334 / 2)];
    imageV.image = blurImage;
    imageV.center = self.view.center;
    [self.view addSubview:imageV];
    
}

方案二:利用UIImage+ImageEffects分類

• 將UIImage+ImageEffects.h和UIImage+ImageEffects.m文件加載進工程
• 包含UIImage+ImageEffects.h
• UIImage+ImageEffects文件路徑

#import "ViewController.h"

#import "UIImage+ImageEffects.h"
- (void)viewDidLoad {
    [super viewDidLoad];

    // 原始圖片
    UIImage *sourceImage = [UIImage imageNamed:@"che"];

    // 對圖片進行模糊處理
    UIImage *blurImage = [sourceImage blurImageWithRadius:10];
    
    // 加載模糊處理后的圖片
    UIImageView *imageV = [[UIImageView alloc] initWithImage:blurImage];
    [self.view addSubview:imageV];

}

方案三:利用UIVisualEffectView(iOS8)

#import "ViewController.h"

@interface ViewController ()

/** 背景 */
@property (nonatomic, strong) UIScrollView *scrollView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // 添加展示的背景,用于顯示動態模糊(背景能夠滾動,便于查看動態的模糊)
    self.scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
    UIImageView *imageV = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"fengjing"]];
    self.scrollView.contentSize = imageV.image.size;
    self.scrollView.bounces = NO;
    [self.scrollView addSubview:imageV];
    [self.view addSubview:self.scrollView];
    
    /***************添加模糊效果***************/
    // 1.創建模糊view
    UIVisualEffectView *effectView = [[UIVisualEffectView alloc] initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleLight]];
    
    // 2.設定模糊View的尺寸
    effectView.frame = CGRectMake(0, 100, 375, 200);
    
    // 3.添加到view當中
    [self.view addSubview:effectView];
    
    
    
    /******************添加顯示文本******************/
    UILabel *label = [[UILabel alloc] initWithFrame:effectView.bounds];
    label.text = @"模糊效果";
    label.font = [UIFont systemFontOfSize:40];
    label.textAlignment = NSTextAlignmentCenter;
    
    /****************添加模糊效果的子view****************/
    // 1.創建出子模糊view
    UIVisualEffectView *subEffectView = [[UIVisualEffectView alloc] initWithEffect:[UIVibrancyEffect effectForBlurEffect:(UIBlurEffect *)effectView.effect]];
    
    // 2.設置子模糊view的尺寸
    subEffectView.frame = effectView.bounds;
    
    // 3.將子模糊view添加到effectView的contentView上才能顯示
    [effectView.contentView addSubview:subEffectView];
    
    // 4.添加要顯示的view來達到特殊效果
    [subEffectView.contentView addSubview:label];
 
}

@end

iOS8-模糊效果.gif