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统一设置UINavigationController左上角图标

方法一

通过工厂方法,然后在需要左上角显示图标的ViewController的viewDidLoad方法调用。代码如下:

Factory.h文件

#import <Foundation/Foundation.h>
@interface Factory : NSObject
+ (void)addBackButton:(UIViewController *)viewController;
@end
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==Factory.m文件==
#import "Factory.h" @implementation Factory + (void)addBackButton:(UIViewController *)viewController{ UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom]; [button setImage:[UIImage imageNamed:@"community_highlight"] forState:UIControlStateNormal]; [button setImage:[UIImage imageNamed:@"community_highlight"] forState:UIControlStateHighlighted]; CGRect frame = button.frame; frame.size = button.currentImage.size; button.frame = frame; UIBarButtonItem *buttonItem = [[UIBarButtonItem alloc]initWithCustomView:button]; UIBarButtonItem *speaceItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil]; speaceItem.width = -5; viewController.navigationItem.leftBarButtonItems = @[speaceItem,buttonItem]; } @end
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### 方法二
这种方法是通过实现UINavigationController的pushViewController方法,拦截所有push进来的viewController,然后对其进行设置。代码如下:

==BaseNavigationController.h文件==
#import <UIKit/UIKit.h> @interface BaseNavigationController : UINavigationController @end
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==BaseNavigationController.m文件==
#import "BaseNavigationController.h" @interface BaseNavigationController () @end @implementation BaseNavigationController - (void)addBackButton:(UIViewController *)viewController{ if (self.viewControllers.count > 0) { viewController.hidesBottomBarWhenPushed = YES; UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom]; [button setImage:[UIImage imageNamed:@"back_icon_red"] forState:UIControlStateNormal]; [button setImage:[UIImage imageNamed:@"back_icon_red"] forState:UIControlStateHighlighted]; [button addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside]; button.size = button.currentImage.size; UIBarButtonItem *buttonItem = [[UIBarButtonItem alloc]initWithCustomView:button]; UIBarButtonItem *speaceItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil]; speaceItem.width = -5; viewController.navigationItem.leftBarButtonItems = @[speaceItem,buttonItem]; } } - (void)back{ [self popViewControllerAnimated:YES]; } - (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated{ NSLog(@"push"); [self addBackButton:viewController]; [super pushViewController:viewController animated:animated]; } #pragma -mark 生命周期 - (void)viewDidLoad { [super viewDidLoad]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; } @end ``` > 注意: 1. 用方法一如果某个viewController需要单独设置navigationItem的图标,则在ViewController的viewDidLoad方法里设置即可。 2. 用了方法二如果在push之前调用设置view样式有关的方法,则先调用viewDidLoad方法,然后调用push方法。这时如果在viewDidLoad方法里设置navigationItem的图标将跟push方法拦截viewController设置的效果一样。 > 所谓的拦截,大部分都是通过自定义类,然后重写自带方法实现的。 **--EOF--**