ios7 setBackButtonBackgroundImage 图像仍然被拉伸(stretch)

Question

使用以下代码设置全局导航后退按钮图像:

float imageSize = 21.5; // @2x is 43px width

UIImage *barBackBtnImg = [[UIImage imageNamed:@"arrow-back-white"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, imageSize, 0, 0)];

[[UIBarButtonItem appearance] setBackButtonBackgroundImage:barBackBtnImg
                                                  forState:UIControlStateNormal
                                                barMetrics:UIBarMetricsDefault];
[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)
                                                     forBarMetrics:UIBarMetricsDefault];

原图:http://cl.ly/XJgD和应用内(被拉伸(stretch)):http://cl.ly/XKc0

为什么图像仍然被拉伸(stretch)有什么想法吗？

Answer 1

如果有人感兴趣，这是我的解决方法:

[[UINavigationBar appearance] setBackIndicatorImage:[UIImage imageNamed:@"arrow-back-white"]];
[[UINavigationBar appearance] setBackIndicatorTransitionMaskImage:[UIImage imageNamed:@"arrow-back-white"]];
[[UINavigationBar appearance] setTintColor:[UIColor whiteColor]];