iOS开发swift版异步加载网络图片(带缓存和缺省图片)

iOS开发之swift版异步加载网络图片

    与SDWebImage异步加载网络图片的功能相似，只是代码比较简单，功能没有SD的完善与强大，支持缺省添加图片，支持本地缓存。

     异步加载图片的核心代码如下：

 func setZYHWebImage(url:NSString?, defaultImage:NSString?, isCache:Bool){          var ZYHImage:UIImage?          if url == nil {              return          }          //设置默认图片          if defaultImage != nil {              self.image=UIImage(named: defaultImage!)          }          //是否进行缓存处理          if isCache {          //缓存管理类              var data:NSData?=ZYHWebImageChcheCenter.readCacheFromUrl(url!)              if data != nil {                  ZYHImage=UIImage(data: data!)                  self.image=ZYHImage              }else{              //获取异步线程                 var dispath=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)                  dispatch_async(dispath, { () -> Void in                      var URL:NSURL = NSURL(string: url!)!                      var data:NSData?=NSData(contentsOfURL: URL)                      if data != nil {                          ZYHImage=UIImage(data: data!)                          //写缓存                          ZYHWebImageChcheCenter.writeCacheToUrl(url!, data: data!)                          //主线程中刷新UI                          dispatch_async(dispatch_get_main_queue(), { () -> Void in                              //刷新主UI                              self.image=ZYHImage                          })                      }                                        })              }          }else{              var dispath=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)              dispatch_async(dispath, { () -> Void in                  var URL:NSURL = NSURL(string: url!)!                  var data:NSData?=NSData(contentsOfURL: URL)                  if data != nil {                      ZYHImage=UIImage(data: data!)                      //写缓存                      dispatch_async(dispatch_get_main_queue(), { () -> Void in                          //刷新主UI                          self.image=ZYHImage                      })                  }                                })          }      }        }

缓存的处理这里采用的是写文件的方式，通过文件名来对缓存进行管理，这个框架还不完善，后面会加入缓存清除等功能。缓存的核心代码如下：

class func readCacheFromUrl(url:NSString)->NSData?{          var data:NSData?          var path:NSString=ZYHWebImageChcheCenter.getFullCachePathFromUrl(url)          if NSFileManager.defaultManager().fileExistsAtPath(path) {              data=NSData.dataWithContentsOfMappedFile(path) as? NSData          }          return data      }            class func writeCacheToUrl(url:NSString, data:NSData){          var path:NSString=ZYHWebImageChcheCenter.getFullCachePathFromUrl(url)         println(data.writeToFile(path, atomically: true))      }      //设置缓存路径      class func getFullCachePathFromUrl(url:NSString)->NSString{          var chchePath=NSHomeDirectory().stringByAppendingString("/Library/Caches/MyCache")          var fileManager:NSFileManager=NSFileManager.defaultManager()          fileManager.fileExistsAtPath(chchePath)          if !(fileManager.fileExistsAtPath(chchePath)) {              fileManager.createDirectoryAtPath(chchePath, withIntermediateDirectories: true, attributes: nil, error: nil)          }          //进行字符串处理          var newURL:NSString          newURL=ZYHWebImageChcheCenter.stringToZYHString(url)          chchePath=chchePath.stringByAppendingFormat("/%@", newURL)          return chchePath      }            class func stringToZYHString(str:NSString)->NSString{          var newStr:NSMutableString=NSMutableString()          for var i:NSInteger=0; i < str.length; i++ {              var c:unichar=str.characterAtIndex(i)              if (c>=48&&c<=57)||(c>=65&&c<=90)||(c>=97&&c<=122){                  newStr.appendFormat("%c", c)              }          }          return newStr.copy() as NSString                }

框架的github地址，欢迎指正与扩展：https://github.com/ZYHshao/swift-ZYHWebImage

因xcode的版本不同，swift语言语法随环境时常会变化，此版本在6.1中可用，更高版本中需要修改少部分即可。