Xcode6编译SDWebImage报SDWebImageDownloaderOperation.m

报错：

    Use of undeclared identifier '_executing'；
    Use of undeclared identifier '_finished'；

解决方法：

在SDWebImageDownloaderOperation类的实现中(@implementation SDWebImageDownloaderOperation{...}下面)添加：

@synthesize executing = _executing ;

@synthesize finished = _finished;