UIImage* img=[UIImage imageNamed:@"name.png"];//原图

UIEdgeInsets edge=UIEdgeInsetsMake(, , ,);

//UIImageResizingModeStretch：拉伸模式，通过拉伸UIEdgeInsets指定的矩形区域来填充图片

//UIImageResizingModeTile：平铺模式，通过重复显示UIEdgeInsets指定的矩形区域来填充图

img= [img resizableImageWithCapInsets:edge resizingMode:UIImageResizingModeStretch];

imageView.image=img;