第一個(gè)方法

  // 1.創(chuàng)建過濾器
 CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];

// 2.恢復(fù)默認(rèn)
[filter setDefaults];

// 3.給過濾器添加數(shù)據(jù)(正則表達(dá)式/賬號(hào)和密碼)
NSString *dataString = @"http://www.520it.com";
NSData *data = [dataString dataUsingEncoding:NSUTF8StringEncoding];
[filter setValue:data forKeyPath:@"inputMessage"];

// 4.獲取輸出的二維碼
CIImage *outputImage = [filter outputImage];

//因?yàn)樯傻亩S碼模糊，所以通過createNonInterpolatedUIImageFormCIImage:outputImage來獲得高清的二維碼圖片
// 5.顯示二維碼
imageView.image = [self createNonInterpolatedUIImageFormCIImage:outputImage withSize:200 string:@"http://www.520it.com"];

第二個(gè)方法：

- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size string:(NSString *)string
{

CGRect extent = CGRectIntegral(image.extent);
CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));

// 1.創(chuàng)建bitmap;
size_t width = CGRectGetWidth(extent) * scale;
size_t height = CGRectGetHeight(extent) * scale;
CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
CGContextScaleCTM(bitmapRef, scale, scale);
CGContextDrawImage(bitmapRef, extent, bitmapImage);

// 2.保存bitmap到圖片
CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
CGContextRelease(bitmapRef);
CGImageRelease(bitmapImage);
return [UIImage imageWithCGImage:scaledImage];

}