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

首先我们需要image的NSData

//Use image name from bundle to create NSData
let image : UIImage = UIImage(named:"imageNameHere")!
//Now use image to create into NSData format
let imageData:NSData = UIImagePNGRepresentation(image)!

//OR next possibility

//Use image's path to create NSData
let url:NSURL = NSURL(string : "urlHere")!
//Now use image to create into NSData format
let imageData:NSData = NSData.init(contentsOfURL: url)!

Swift 2.0 >编码

let strBase64:String = imageData.base64EncodedStringWithOptions(.Encoding64CharacterLineLength)

Swift 2.0 >解码

let dataDecoded:NSData = NSData(base64EncodedString: strBase64, options: NSDataBase64DecodingOptions.IgnoreUnknownCharacters)!

Swift 3.0 >解码

let dataDecoded : Data = Data(base64Encoded: strBase64, options: .ignoreUnknownCharacters)!

编码:

let strBase64 = imageData.base64EncodedString(options: .lineLength64Characters)
print(strBase64)

解码:

let dataDecoded:NSData = NSData(base64EncodedString: strBase64, options: NSDataBase64DecodingOptions(rawValue: 0))!
let decodedimage:UIImage = UIImage(data: dataDecoded)!
print(decodedimage)
yourImageView.image = decodedimage

斯威夫特3.0

let dataDecoded : Data = Data(base64Encoded: strBase64, options: .ignoreUnknownCharacters)!
let decodedimage = UIImage(data: dataDecoded)
yourImageView.image = decodedimage

---

objective - c

iOS7 >版本

你可以使用NSData的base64EncodedStringWithOptions

编码:

- (NSString *)encodeToBase64String:(UIImage *)image {
 return [UIImagePNGRepresentation(image) base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
}

解码:

- (UIImage *)decodeBase64ToImage:(NSString *)strEncodeData {
  NSData *data = [[NSData alloc]initWithBase64EncodedString:strEncodeData options:NSDataBase64DecodingIgnoreUnknownCharacters];
  return [UIImage imageWithData:data];
}

---

iOS 6.1和<版本

第一个选项:使用这个链接来编码和解码图像

在项目中添加Base64类。

编码:

 NSData* data = UIImageJPEGRepresentation(yourImage, 1.0f);
 NSString *strEncoded = [Base64 encode:data];

解码:

 NSData* data = [Base64 decode:strEncoded ];;
 image.image = [UIImage imageWithData:data];

另一种选择:使用qutilities进行编码和解码

---

在Swift 3.0中

func decodeBase64(toImage strEncodeData: String) -> UIImage {

    let dataDecoded  = NSData(base64Encoded: strEncodeData, options: NSData.Base64DecodingOptions.ignoreUnknownCharacters)!
    let image = UIImage(data: dataDecoded as Data)
    return image!

}

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)

Swift 4.2 | Xcode 10

extension UIImage {

    /// EZSE: Returns base64 string
    public var base64: String {
        return self.jpegData(compressionQuality: 1.0)!.base64EncodedString()
    }
}

Swift版本-创建base64镜像

在我看来，在UIImagePNGRepresenatation()的情况下隐式Unwrapped Optional是不安全的，所以我建议使用扩展如下:

extension UIImage {

    func toBase64() -> String? {
        let imageData = UIImagePNGRepresentation(self)
        return imageData?.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.Encoding64CharacterLineLength)
    }
}