iPhone SDK:如何将图像添加到UIBarButton？

Question

我使用下面的代码在导航栏上创建一个带有图像的按钮.

我可以看到图像,但我也可以看到它周围按钮的边框.我的问题是,如何摆脱按钮边框.我想看到的只是导航栏上的图像,没有边框.

UIBarButtonItem *settingsBtn = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"icon_prefs.png"] style:UIBarButtonItemStylePlain target:self action:@selector(openSettings:)];
[[self navigationItem] setLeftBarButtonItem:settingsBtn];
[settingsBtn release];

提前致谢.任何指针,进一步阅读的链接或赞赏的例子.

Answer 1

这是我当前项目之一的代码片段.它为以下内容加载具有透明度的图像UIBarButtonItem:

UIImage* image = [UIImage imageNamed:@"some-image.png"];
CGRect frame = CGRectMake(0, 0, image.size.width, image.size.height);
UIButton* someButton = [[UIButton alloc] initWithFrame:frame];
[someButton setBackgroundImage:image forState:UIControlStateNormal];
[someButton setShowsTouchWhenHighlighted:YES];
UIBarButtonItem* someBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:someButton];
[self.navigationItem setRightBarButtonItem:someBarButtonItem];
[someBarButtonItem release];
[someButton release];