• 导航栏，很多都设置单个图标相同的效果，怎么封装？
  • 写个工具类（继承NSObject）：
  • 坏处：
    • 增加了一个新的类
    • 不易于理解，因为该功能属于UIBarButtonItem的功能。

#import "JPItemTool.h"

@implementation JPItemTool
+ (UIBarButtonItem *)itemWithImage:(NSString *)image highImage:(NSString *)highImage target:(id)target action:(SEL)action
{
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setBackgroundImage:[UIImage imageNamed:image] forState:UIControlStateNormal];
    [button setBackgroundImage:[UIImage imageNamed:highImage] forState:UIControlStateHighlighted];
    [button sizeToFit];
    [button addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];
    
    return [[UIBarButtonItem alloc] initWithCustomView:button];
}
@end

• UIBarButton的扩展分类：

- 好处：
  + 不会增加新的类
  + 易于理解
  + 调用合理

#import "UIBarButtonItem+JPExtension.h"

@implementation UIBarButtonItem (JPExtension)
+ (instancetype)itemWithImage:(NSString *)image highImage:(NSString *)highImage target:(id)target action:(SEL)action
{
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setBackgroundImage:[UIImage imageNamed:image] forState:UIControlStateNormal];
    [button setBackgroundImage:[UIImage imageNamed:highImage] forState:UIControlStateHighlighted];
    [button sizeToFit];
    [button addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];
    
    return [[self alloc] initWithCustomView:button];
}
@end

• 使用分类，设置导航栏按钮

 // 导航栏右边的内容
    UIBarButtonItem *moonItem = [UIBarButtonItem itemWithImage:@"mine-moon-icon" highImage:@"mine-moon-icon-click" target:self action:@selector(moonClick)];