swift 判断html图片,Swift 5.3 判断图片类型

在实际开发中，有时候会碰到图片类型不确定，需要判断图片类型进行其他操作，因此直接给Data做一个扩展，支持检测图片的类型。

扩展支持jpeg tiff bmp ico icns gif png webp等多种格式的图片类型判断。

从图片数据中截取第一个16进制数据，然后比对判断。

extension Data {

enum ImageType {

case unknown

case jpeg

case tiff

case bmp

case ico

case icns

case gif

case png

case webp

}

func detectImageType() -> Data.ImageType {

if self.count < 16 { return .unknown }

var value = [UInt8](repeating:0, count:1)

self.copyBytes(to: &value, count: 1)

switch value[0] {

case 0x4D, 0x49:

return .tiff

case 0x00:

return .ico

case 0x69:

return .icns

case 0x47:

return .gif

case 0x89:

return .png

case 0xFF:

return .jpeg

case 0x42:

return .bmp

case 0x52:

let subData = self.subdata(in: Range(NSMakeRange(0, 12))!)

if let infoString = String(data: subData, encoding: .ascii) {

if infoString.hasPrefix("RIFF") && infoString.hasSuffix("WEBP") {

return .webp

}

}

break

default:

break

}

return .unknown

}

static func detectImageType(with data: Data) -> Data.ImageType {

return data.detectImageType()

}

static func detectImageType(with url: URL) -> Data.ImageType {

if let data = try? Data(contentsOf: url) {

return data.detectImageType()

} else {

return .unknown

}

}

static func detectImageType(with filePath: String) -> Data.ImageType {

let pathUrl = URL(fileURLWithPath: filePath)

if let data = try? Data(contentsOf: pathUrl) {

return data.detectImageType()

} else {

return .unknown

}

}

static func detectImageType(with imageName: String, bundle: Bundle = Bundle.main) -> Data.ImageType? {

guard let path = bundle.path(forResource: imageName, ofType: "") else { return nil }

let pathUrl = URL(fileURLWithPath: path)

if let data = try? Data(contentsOf: pathUrl) {

return data.detectImageType()

} else {

return nil

}

}

}