原有的问题如下

Xnip2022-01-06_10-29-40.jpg

解决之后

Xnip2022-01-06_10-29-55.jpg

解决方案如下

self.loginButton.layer.cornerRadius = 5;
   self.loginButton.clipsToBounds = YES;
   
   //让背景图片不要拉伸
   UIImage *image = _loginButton.currentBackgroundImage;
   image = [image stretchableImageWithLeftCapWidth:image.size.width / 2 topCapHeight:image.size.height / 2];
   [_loginButton setBackgroundImage:image forState:UIControlStateNormal];
   [self.loginButton setBackgroundImage:image forState:UIControlStateHighlighted];
   

放在viewDidLoad调用