ios程序中异常处理问题

[NSCFconstantString isResizable],这个异常要怎么解决,这是我用NSString类型给UIImage赋值时出现的错误

http://www.cocoachina.com/ios/20141229/10787.html

具体代码怎么写的,
UIImage.image = UIImage("named": xxx)

http://www.cocoachina.com/ios/20141229/10787.html