ios - 有没有办法在 iOS 上生成二维码图像

Question

是否有一种标准方法可以生成 QR 码并将其附加到来自 iOS 客户端应用程序的邮件项目（无服务器代码）？

Answer 1

从 iOS 7 开始，您可以使用 Core Image 过滤器来生成 QR 图像。请参阅此处的最终提示：

- (CIImage *)createQRForString:(NSString *)qrString {
    NSData *stringData = [qrString dataUsingEncoding: NSISOLatin1StringEncoding];

    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [qrFilter setValue:stringData forKey:@"inputMessage"];

    return qrFilter.outputImage;
}

Answer 2

对于完美适合我的 Obj-C 版本，我混合了答案 पवन 和 Teja Kumar Bethina：

NSString *qrString = @"My string to encode";
NSData *stringData = [qrString dataUsingEncoding: NSUTF8StringEncoding];

CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
[qrFilter setValue:stringData forKey:@"inputMessage"];
[qrFilter setValue:@"H" forKey:@"inputCorrectionLevel"];

CIImage *qrImage = qrFilter.outputImage;
float scaleX = self.qrImageView.frame.size.width / qrImage.extent.size.width;
float scaleY = self.qrImageView.frame.size.height / qrImage.extent.size.height;

qrImage = [qrImage imageByApplyingTransform:CGAffineTransformMakeScale(scaleX, scaleY)];

self.qrImageView.image = [UIImage imageWithCIImage:qrImage
                                             scale:[UIScreen mainScreen].scale
                                       orientation:UIImageOrientationUp];

Answer 3

使用斯威夫特 2

import UIKit
import CoreImage

func createQRFromString(str: String) -> CIImage? {
    let stringData = str.dataUsingEncoding(NSUTF8StringEncoding)
    
    let filter = CIFilter(name: "CIQRCodeGenerator")
    
    filter?.setValue(stringData, forKey: "inputMessage")
    
    filter?.setValue("H", forKey: "inputCorrectionLevel")
    
    return filter?.outputImage
}

if let img = createQRFromString("Hello world program created by someone") {
    let somImage = UIImage(CIImage: img, scale: 1.0, orientation: UIImageOrientation.Down)
}

斯威夫特 3.0

import UIKit
import CoreImage

func createQRFromString(_ str: String) -> CIImage? {
        let stringData = str.data(using: String.Encoding.utf8)
        
        let filter = CIFilter(name: "CIQRCodeGenerator")
        
        filter?.setValue(stringData, forKey: "inputMessage")
        
        filter?.setValue("H", forKey: "inputCorrectionLevel")
        
        if let img = createQRFromString("Hello world program created by someone") {
            let somImage = UIImage(ciImage: img, scale: 1.0, orientation: UIImageOrientation.down)
        }
        
        return filter?.outputImage
    }

if let img = createQRFromString("Hello world program created by someone") {
            let somImage = UIImage(ciImage: img, scale: 1.0, orientation: UIImageOrientation.down)
        }

斯威夫特 4.2

private func createQRFromString(str: String) -> CIImage? {
        let stringData = str.data(using: .utf8)
        
        let filter = CIFilter(name: "CIQRCodeGenerator")
        filter?.setValue(stringData, forKey: "inputMessage")
        filter?.setValue("H", forKey: "inputCorrectionLevel")
        
        return filter?.outputImage
    }
    
    var qrCode: UIImage? {
        if let img = createQRFromString(str: "Hello world program created by someone") {
            let someImage = UIImage(
                ciImage: img,
                scale: 1.0,
                orientation: UIImage.Orientation.down
            )
            return someImage
        }
        
        return nil
    }

Xcode 12.4 或 Swift 版本 >= 5.2

import UIKit
import CoreImage

func createQRFromString(str: String) -> CIImage? {
  let stringData = str.data(using: .utf8)
  
  let filter = CIFilter(name: "CIQRCodeGenerator")
  
  filter?.setValue(stringData, forKey: "inputMessage")
  
  filter?.setValue("H", forKey: "inputCorrectionLevel")
  
  return filter?.outputImage
}

if let img = createQRFromString(str: "Hello world program created by someone") {
  let somImage = UIImage(ciImage: img, scale: 1.0, orientation: .down)
}

Answer 4

自从提出这个问题以来已经有一段时间了，并且已经给出了一些几乎完美的答案。但是，我必须调整并结合几个答案，才能让它在 2018 年使用 Xcode 9.2 完美适用于 AppleTV 4K、iPhone X 和 iPadPro。如果有人需要，这里是代码。

@IBOutlet weak var qrCodeBox: UIImageView!

func createQRFromString(_ str: String, size: CGSize) -> UIImage {
    let stringData = str.data(using: .utf8)

  let qrFilter = CIFilter(name: "CIQRCodeGenerator")!
  qrFilter.setValue(stringData, forKey: "inputMessage")
  qrFilter.setValue("H", forKey: "inputCorrectionLevel")

  let minimalQRimage = qrFilter.outputImage!
  // NOTE that a QR code is always square, so minimalQRimage..width === .height
  let minimalSideLength = minimalQRimage.extent.width

  let smallestOutputExtent = (size.width < size.height) ? size.width : size.height
  let scaleFactor = smallestOutputExtent / minimalSideLength
  let scaledImage = minimalQRimage.transformed(
    by: CGAffineTransform(scaleX: scaleFactor, y: scaleFactor))

  return UIImage(ciImage: scaledImage, 
                 scale: UIScreen.main.scale, 
                 orientation: .up)
}

override func viewDidLoad() {
    super.viewDidLoad()
    let myQRimage = createQRFromString("https://www.apple.com", 
                      size: qrCodeBox.frame.size)
    qrCodeBox.image = myQRimage
}

Answer 5

在 Swift 2.0 中生成 QR 图像的代码。

let reqStr = “string to convert as QR code”
let data = reqStr.dataUsingEncoding(NSISOLatin1StringEncoding, allowLossyConversion: false)

let filter = CIFilter(name: "CIQRCodeGenerator")
filter!.setValue(data, forKey: "inputMessage")

let qrImage:CIImage = filter!.outputImage!

//qrImageView is a IBOutlet of UIImageView        
let scaleX = qrImageView.frame.size.width / qrImage.extent.size.width
let scaleY = qrImageView.frame.size.height / qrImage.extent.size.height

let resultQrImage = qrImage.imageByApplyingTransform(CGAffineTransformMakeScale(scaleX, scaleY))
qrImageView.image = UIImage(CIImage: resultQrImage)

Answer 6

...这将让我生成链接...

首先，您需要找到一个短链接服务，例如bit.ly或goo.by，以使长链接更短，从而减少 QR 码的大小。

要自动执行此任务，您必须使用一些 Web 服务。

...然后生成一个二维码...

ZXing是一个流行的开源二维码生成器，也可用于 iOS

Answer 7

如果您不介意使用公共 api，这里有一个简单的 10 秒方法。http://goqr.me/api

只需填写数据参数，然后从响应中加载图像。干杯。

Answer 8

我为 Obj-C 创建了一个 NSString 类别，以 Mike Demidov 的精彩回答

NString+GGQRCode.h

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface NSString (GGQRCode)

-(UIImage *)qrCodeImage:(CGFloat)width height:(CGFloat)height;
-(UIImage *)qrCodeImage:(CGFloat)width height:(CGFloat)height scale:(CGFloat)scale orientation:(UIImageOrientation)orientation;

@end

NString+GGQRCode.m

#import "NSString+GGQRCode.h"

@implementation NSString (GGQRCode)

-(UIImage *)qrCodeImage:(CGFloat)width height:(CGFloat)height
{
    return [self qrCodeImage:width height:height scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp];
}

-(UIImage *)qrCodeImage:(CGFloat)width height:(CGFloat)height scale:(CGFloat)scale orientation:(UIImageOrientation)orientation
{
    NSData *stringData = [self dataUsingEncoding: NSUTF8StringEncoding];

    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [qrFilter setValue:stringData forKey:@"inputMessage"];
    [qrFilter setValue:@"H" forKey:@"inputCorrectionLevel"];

    CIImage *qrImage = qrFilter.outputImage;
    float scaleX = width / qrImage.extent.size.width;
    float scaleY = height / qrImage.extent.size.height;

    qrImage = [qrImage imageByApplyingTransform:CGAffineTransformMakeScale(scaleX, scaleY)];

    return [UIImage imageWithCIImage:qrImage scale:scale orientation:orientation];
}

@end