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; } } }
