UIImage *img2=[UIImage imageNamed:@"course_bg.png"];
img2=[img2 stretchableImageWithLeftCapWidth:15 topCapHeight:12];
[_backImageView setImage:img2];
UIImage *img2=[UIImage imageNamed:@"course_bg.png"];
img2=[img2 stretchableImageWithLeftCapWidth:15 topCapHeight:12];
[_backImageView setImage:img2];