Swift 3.0和Xcode 8.0

let imageData = UIImageJPEGRepresentation(imageView.image!, 1)

    let base64String = (imageData! as Data).base64EncodedString(options: NSData.Base64EncodingOptions(rawValue: 0))
    print(base64String)

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)

我尝试了所有的解决方案，没有一个对我有效(使用Swift 4)，这是对我有效的解决方案，如果将来有人面临同样的问题。

let temp = base64String.components(separatedBy: ",")
let dataDecoded : Data = Data(base64Encoded: temp[1], options: 
 .ignoreUnknownCharacters)!
let decodedimage = UIImage(data: dataDecoded)

yourImage.image = decodedimage

斯威夫特5。

class ImageConverter {

    func base64ToImage(_ base64String: String) -> UIImage? {
        guard let imageData = Data(base64Encoded: base64String) else { return nil }
        return UIImage(data: imageData)
    }

    func imageToBase64(_ image: UIImage) -> String? {
        return image.jpegData(compressionQuality: 1)?.base64EncodedString()
    }

}

在Swift 3.0和Xcode 8.0

编码:

let userImage:UIImage = UIImage(named: "Your-Image_name")!
let imageData:NSData = UIImagePNGRepresentation(userImage)! as NSData
let dataImage = imageData.base64EncodedString(options: .lineLength64Characters)

解码:

let imageData = dataImage
let dataDecode:NSData = NSData(base64Encoded: imageData!, options:.ignoreUnknownCharacters)!
let avatarImage:UIImage = UIImage(data: dataDecode as Data)!
yourImageView.image = avatarImage

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
    }
}