小编给大家分享一下iOS11中如何使用两种方法替换Method Swizzling去掉导航栏返回按钮的文字,相信大部分人都还不怎么了解,因此分享这篇文章给大家参考一下,希望大家阅读完这篇文章后大有收获,下面让我们一起去了解一下吧!
方法一:设置BarButtonItem的文本样式为透明颜色,代码如下:
[[UIBarButtonItem appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName: [UIColor clearColor]} forState:UIControlStateNormal]; [[UIBarButtonItem appearance] setTitleTextAttributes:@{NSForegroundColorAttributeName: [UIColor clearColor]} forState:UIControlStateHighlighted];
此外这种方法会导致title不能居中,被偏移很多,如下所示(虽然不被显示,也占了导航栏左边很大一部分位置)
方法二:给UIViewController添加类别,然后在load方法里面用Method Swzilling方法替换 交换ViewDidAppear,部分代码如下
+(void)load { swizzleMethod([self class], @selector(viewDidAppear:), @selector(ac_viewDidAppear)); } - (void)ac_viewDidAppear{ self.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStylePlain target:self action:nil]; [self ac_viewDidAppear]; } void swizzleMethod(Class class, SEL originalSelector, SEL swizzledSelector) { // the method might not exist in the class, but in its superclass Method originalMethod = class_getInstanceMethod(class, originalSelector); Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector); // class_addMethod will fail if original method already exists BOOL didAddMethod = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod)); // the method doesn't exist and we just added one if (didAddMethod) { class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod)); } else { method_exchangeImplementations(originalMethod, swizzledMethod); } }
注意事项:
要给整个backButtonItem赋值才可以,?这种方法不行,因为backBarButtonItem默认为空,给nil方法消息,默认声明都不执行(参考官网)
self.navigationItem.backBarButtonItem.title = @" ";
leftBarButtonItem 与backBarButtonItem 的显示关系:
有leftBarButtonItem则优先显示当前VC的leftBarButtonItem,无则显示上个VC的backBarButtonItem,再无则显示上个VC的title(参考官网 还是官网解释的清楚)
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