斯威夫特5

编码

func convertImageToBase64String (img: UIImage) -> String {
    return img.jpegData(compressionQuality: 1)?.base64EncodedString() ?? ""
}

解码

func convertBase64StringToImage (imageBase64String:String) -> UIImage {
    let imageData = Data(base64Encoded: imageBase64String)
    let image = UIImage(data: imageData!)
    return image!
}

注意:在xcode 10.2中测试

斯威夫特4

编码

func convertImageToBase64String (img: UIImage) -> String {
    let imageData:NSData = UIImageJPEGRepresentation(img, 0.50)! as NSData //UIImagePNGRepresentation(img)
    let imgString = imageData.base64EncodedString(options: .init(rawValue: 0))
    return imgString
}

解码

func convertBase64StringToImage (imageBase64String:String) -> UIImage {
    let imageData = Data.init(base64Encoded: imageBase64String, options: .init(rawValue: 0))
    let image = UIImage(data: imageData!)
    return image
}

注意:在xcode 9.4.1中测试

对于iOS 7+， Objective-C，下面是如何从一个图像URL开始转换:

NSURL *url = [NSURL URLWithString:self.groove.thumbnailURL];

UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:url]];

NSString *base64String = [UIImagePNGRepresentation(image)
base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];

很好理解你是否传递了Tyler Sheaffer所说的前缀。 但出于某种原因，你可能需要这个前缀来描述base64字符串开头的mime类型，所以我建议这段代码在编码之前传递一些选项(Swift 5):

extension UIImage {

    enum Format: String {
        case png = "png"
        case jpeg = "jpeg"
    }

    func toBase64(type: Format = .jpeg, quality: CGFloat = 1, addMimePrefix: Bool = false) -> String? {
        let imageData: Data?
        switch type {
        case .jpeg: imageData = jpegData(compressionQuality: quality)
        case .png:  imageData = pngData()
        }
        guard let data = imageData else { return nil }

        let base64 = data.base64EncodedString(options: Data.Base64EncodingOptions.lineLength64Characters)

        var result = base64
        if addMimePrefix {
            let prefix = "data:image/\(type.rawValue);base64,"
            result = prefix + base64
        }
        return result
    }
}

斯威夫特4

enum ImageFormat {
    case png
    case jpeg(CGFloat)
}

extension UIImage {
    func base64(format: ImageFormat) -> String? {
        var imageData: Data?

        switch format {
        case .png: imageData = UIImagePNGRepresentation(self)
        case .jpeg(let compression): imageData = UIImageJPEGRepresentation(self, compression)
        }

        return imageData?.base64EncodedString()
    }
}

extension String {
    func imageFromBase64() -> UIImage? {
        guard let data = Data(base64Encoded: self) else { return nil }

        return UIImage(data: data)
    }
}

斯威夫特3.0

将图像转换为base64字符串

操场测试

    var logo = UIImage(named: "image_logo")
    let imageData:Data =  UIImagePNGRepresentation(logo)
    let base64String = imageData.base64EncodedString()
    print(base64String)

解码使用方便的初始化器- Swift 5

extension UIImage {
    convenience init?(base64String: String) {
        guard let data = Data(base64Encoded: base64String) else { return nil }
        self.init(data: data)
    }
}