斯威夫特iOS8

// prgm mark ---- 

// convert images into base64 and keep them into string

func convertImageToBase64(image: UIImage) -> String {

    var imageData = UIImagePNGRepresentation(image)
    let base64String = imageData.base64EncodedStringWithOptions(.allZeros)

    return base64String

}// end convertImageToBase64


// prgm mark ----

// convert images into base64 and keep them into string

func convertBase64ToImage(base64String: String) -> UIImage {

    let decodedData = NSData(base64EncodedString: base64String, options: NSDataBase64DecodingOptions(rawValue: 0) )

    var decodedimage = UIImage(data: decodedData!)

    return decodedimage!

}// end convertBase64ToImage

斯威夫特iOS8

// prgm mark ---- 

// convert images into base64 and keep them into string

func convertImageToBase64(image: UIImage) -> String {

    var imageData = UIImagePNGRepresentation(image)
    let base64String = imageData.base64EncodedStringWithOptions(.allZeros)

    return base64String

}// end convertImageToBase64


// prgm mark ----

// convert images into base64 and keep them into string

func convertBase64ToImage(base64String: String) -> UIImage {

    let decodedData = NSData(base64EncodedString: base64String, options: NSDataBase64DecodingOptions(rawValue: 0) )

    var decodedimage = UIImage(data: decodedData!)

    return decodedimage!

}// end convertBase64ToImage

@implementation UIImage (Extended)

- (NSString *)base64String {
    NSData * data = [UIImagePNGRepresentation(self) base64EncodedDataWithOptions:NSDataBase64Encoding64CharacterLineLength];
    return [NSString stringWithUTF8String:[data bytes]];
}

@end

See my class -  AppExtension.swift


// MARK: - UIImage (Base64 Encoding)

public enum ImageFormat {
    case PNG
    case JPEG(CGFloat)
}

extension UIImage {

    public func base64(format: ImageFormat) -> String {
        var imageData: NSData
        switch format {
        case .PNG: imageData = UIImagePNGRepresentation(self)
        case .JPEG(let compression): imageData = UIImageJPEGRepresentation(self, compression)
        }
        return imageData.base64EncodedStringWithOptions(.allZeros)
    }
}

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)
    }
} 

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