Swift － 根据图片URL获取图片的大小

该方法在swift3以后会报大量的错，博主会在近期针对swift3.0进行更正

在swift3.0中，可以下载下来后再用，方法有多种，殊途同归，都是要先下载的，这里提供两种：

方法1:        var urlStr = NSURL(string: "http://ww3.sinaimg.cn/mw690/51f76ed7jw1e3ohzmmnffj.jpg")!        var request = NSURLRequest(url: urlStr as URL)        var imgData = try! NSURLConnection.sendSynchronousRequest(request as URLRequest, returning: nil)        var img: UIImage? = nil        var imageView1 = UIImageView()        if imgData != nil {            img = UIImage(data: imgData)!            imageView1.image = img            print("width:" + "\(img?.size.width)" + "height:" + "\(img?.size.height)")        }方法2:    let lhhImageView = UIImageView()        lhhImageView.sd_setImage(with: URL(string: "http://ww3.sinaimg.cn/mw690/51f76ed7jw1e3ohzmmnffj.jpg")) { (image, error, cacheType, imageURL) in            print("width:" + "\(image?.size.width)" + "height:" + "\(image?.size.height)")        }        self.view.addSubview(lhhImageView)

看代码：

  func getImageSize(imageURL:String) ->CGSize {        var URL:NSURL?        if imageURL.isKindOfClass(NSString) {            URL = NSURL(string: imageURL)        }        if URL == nil        {            return  CGSizeZero             // url不正确        }        let request = NSMutableURLRequest(URL: URL!)        let pathExtendsion = URL?.pathExtension?.lowercaseString        var size = CGSizeZero        if pathExtendsion == "png" {            size = self.getPNGImageSize(request)        }        else if pathExtendsion == "gif"        {            size = self.getGIFImageSize(request)        }        else{            size = self.getJPGImageSize(request)        }        if CGSizeEqualToSize(CGSizeZero, size)                   // 如果获取文件头信息失败,发送异步请求请求原图        {            guard let data = try? NSURLConnection.sendSynchronousRequest(request, returningResponse: nil) else{                return size            }            let image = UIImage(data: data)            if image != nil {                size = (image?.size)!            }        }        return size    }    func getPNGImageSize(request:NSMutableURLRequest) -> CGSize {        //  获取PNG图片的大小        request.setValue("bytes=16-23", forHTTPHeaderField: "Range")        guard let data = try? NSURLConnection.sendSynchronousRequest(request, returningResponse: nil) else{            return CGSizeZero        }        if data.length == 8 {            var w1:Int = 0            var w2:Int = 0            var w3:Int = 0            var w4:Int = 0            data.getBytes(&w1, range: NSMakeRange(0, 1))            data.getBytes(&w2, range: NSMakeRange(1, 1))            data.getBytes(&w3, range: NSMakeRange(2, 1))            data.getBytes(&w4, range: NSMakeRange(3, 1))            let w = (w1 << 24) + (w2 << 16) + (w3 << 8) + w4            var h1:Int = 0            var h2:Int = 0            var h3:Int = 0            var h4:Int = 0            data.getBytes(&h1, range: NSMakeRange(4, 1))            data.getBytes(&h2, range: NSMakeRange(5, 1))            data.getBytes(&h3, range: NSMakeRange(6, 1))            data.getBytes(&h4, range: NSMakeRange(7, 1))            let h = (h1 << 24) + (h2 << 16) + (h3 << 8) + h4            return CGSizeMake(CGFloat(w), CGFloat(h));        }        return CGSizeZero;    }    func getGIFImageSize(request:NSMutableURLRequest) -> CGSize {        //  获取GIF图片的大小        request.setValue("bytes=6-9", forHTTPHeaderField: "Range")        guard var data = try? NSURLConnection.sendSynchronousRequest(request, returningResponse: nil) else{            return CGSizeZero        }        if data.length == 4 {            var w1:Int = 0            var w2:Int = 0            data.getBytes(&w1, range: NSMakeRange(0, 1))            data.getBytes(&w2, range: NSMakeRange(1, 1))            var w = w1 + (w2 << 8)            var h1:Int = 0            var h2:Int = 0            data.getBytes(&h1, range: NSMakeRange(2, 1))            data.getBytes(&h2, range: NSMakeRange(3, 1))            var h = h1 + (h2 << 8)            return CGSizeMake(CGFloat(w), CGFloat(h));        }        return CGSizeZero;    }    func getJPGImageSize(request:NSMutableURLRequest) -> CGSize {        //  获取JPG图片的大小        request.setValue("bytes=0-209", forHTTPHeaderField: "Range")        guard var data = try? NSURLConnection.sendSynchronousRequest(request, returningResponse: nil) else{            return CGSizeZero        }        if data.length <= 0x58 {            return CGSizeZero        }        if data.length < 210 {            var w1:Int = 0            var w2:Int = 0            data.getBytes(&w1, range: NSMakeRange(0x60, 0x1))            data.getBytes(&w2, range: NSMakeRange(0x61, 0x1))            var w = (w1 << 8) + w2            var h1:Int = 0            var h2:Int = 0            data.getBytes(&h1, range: NSMakeRange(0x5e, 0x1))            data.getBytes(&h2, range: NSMakeRange(0x5f, 0x1))            var h = (h1 << 8) + h2            return CGSizeMake(CGFloat(w), CGFloat(h));        }        else        {            var word = 0x0            data.getBytes(&word, range: NSMakeRange(0x15, 0x1))            if word == 0xdb {                data.getBytes(&word, range: NSMakeRange(0x5a, 0x1))                if word == 0xdb {                    var w1:Int = 0                    var w2:Int = 0                    data.getBytes(&w1, range: NSMakeRange(0xa5, 0x1))                    data.getBytes(&w2, range: NSMakeRange(0xa6, 0x1))                    var w = (w1 << 8) + w2                    var h1:Int = 0                    var h2:Int = 0                    data.getBytes(&h1, range: NSMakeRange(0xa3, 0x1))                    data.getBytes(&h2, range: NSMakeRange(0xa4, 0x1))                    var h = (h1 << 8) + h2                    return CGSizeMake(CGFloat(w), CGFloat(h));                }                else                {                    var w1:Int = 0                    var w2:Int = 0                    data.getBytes(&w1, range: NSMakeRange(0x60, 0x1))                    data.getBytes(&w2, range: NSMakeRange(0x61, 0x1))                    var w = (w1 << 8) + w2                    var h1:Int = 0                    var h2:Int = 0                    data.getBytes(&h1, range: NSMakeRange(0x5e, 0x1))                    data.getBytes(&h2, range: NSMakeRange(0x5f, 0x1))                    var h = (h1 << 8) + h2                    return CGSizeMake(CGFloat(w), CGFloat(h));                }            }            else {                return CGSizeZero;            }        }    }