二维码的生成

#import "ViewController.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
  
//  使用coreImage框架中的滤镜来实现生成的二维码
//  kCICategoryBuiltIn 内置的过滤器的分类
//    NSArray *filters = [CIFilter filterNamesInCategory:kCICategoryBuiltIn];
//    NSLog(@"%@",filters);
    
//  1.创建一个用于生成二维码的滤镜
    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    
//  2.设置默认值
    [qrFilter setDefaults];
    
//  3.设置输入数据
//    NSLog(@"%@",qrFilter.inputKeys);
    
    [qrFilter setValue:[@"123" dataUsingEncoding:NSUTF8StringEncoding] forKey:@"inputMessage"];
    
//  4.生成图片
    CIImage *ciImage = qrFilter.outputImage;
//  默认生成的ciImage的大小是很小
//    NSLog(@"%@",ciImage);
    
//  放大ciImage
    CGAffineTransform scale = CGAffineTransformMakeScale(8, 8);
    ciImage = [ciImage imageByApplyingTransform:scale];
    
//  5.设置二维码的前景色和背景色
    CIFilter *colorFilter = [CIFilter filterWithName:@"CIFalseColor"];
//  设置默认值
    [colorFilter setDefaults];
    
//  设置输入的值
    /*
     inputImage,
     inputColor0,
     inputColor1
     
     */
//    NSLog(@"%@",colorFilter.inputKeys);
    [colorFilter setValue:ciImage forKey:@"inputImage"];
    
//  设置前景色
    [colorFilter setValue:[CIColor colorWithRed:1 green:0 blue:0] forKey:@"inputColor0"];
//  设置背景
      [colorFilter setValue:[CIColor colorWithRed:0 green:0 blue:1] forKey:@"inputColor1"];
//  取出colorFilter中的图片
    ciImage = colorFilter.outputImage;
    
//  在中心增加一张图片
    UIImage *image = [UIImage imageWithCIImage:ciImage];
    
//  生成图片
//  1.开启图片的上下文
    UIGraphicsBeginImageContext(image.size);
//  2.把二维码的图片划入
    [image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];
//  3.在中心画其他图片
    UIImage *weiImage = [UIImage imageNamed:@"图片名称"];
    CGFloat weiW = 40;
    CGFloat weiH = 40;
    CGFloat weiX = (image.size.width - weiW) * 0.5;
    CGFloat weiY = (image.size.height - weiH) * 0.5;
    
    [weiImage drawInRect:CGRectMake(weiX, weiY, weiW, weiH)];
    
//  取出图片
    UIImage *qrImage =  UIGraphicsGetImageFromCurrentImageContext();
    
//  结束上下文
    UIGraphicsEndImageContext();
    
    self.imageView.image = qrImage;
}