iphone 在类别中添加一个属性

iphone的类别中，只能扩展函数，不能扩展类别。

看可以用下边方法为类别添加方法

头文件：

@interface UINavigationItem (JTRevealSidebarV2)@end

实现文件：

@implementation UINavigationItem (JTRevealSidebarV2)static char *revealSidebarDelegateKey;- (void)setRevealSidebarDelegate:(id<JTRevealSidebarV2Delegate>)revealSidebarDelegate {    objc_setAssociatedObject(self, &revealSidebarDelegateKey, revealSidebarDelegate, OBJC_ASSOCIATION_ASSIGN);}- (id <JTRevealSidebarV2Delegate>)revealSidebarDelegate {    return (id <JTRevealSidebarV2Delegate>)objc_getAssociatedObject(self, &revealSidebarDelegateKey);}@end