UIImage *img = [UIImage imageNamed:@"hehe"];
    
    CGFloat top = 166; //顶端盖高度
    CGFloat bottom = 166 ; //底端盖高度
    CGFloat left = 10; //左端盖宽度
    CGFloat right = 10; //右端盖宽度
    UIEdgeInsets insets = UIEdgeInsetsMake(top, left, bottom, right);
    img = [img resizableImageWithCapInsets:insets resizingMode:UIImageResizingModeStretch];
    
    UIImageView *view = [[UIImageView alloc] initWithImage:img];
    view.frame = CGRectMake(50, 100, 150, 600);
    [self.view addSubview:view];

hehe原图 图片分辨率：1500 * 1500
内容 9宫格 等宽等高

设置拉伸后 这样保证上下不拉伸 只拉伸中间部分