IOS 切换应用闪动

出现这个问题的原因：由于设置nav返回不需要文字

//注:添加此方法，切换应用会出现一闪

[barItem setBackButtonTitlePositionAdjustment:UIOffsetMake(NSIntegerMin,NSIntegerMin)forBarMetrics:UIBarMetricsDefault];

解决方法：

第一种方法：在parent viewController中的viewDidLoad配置如下：

- (void)viewDidLoad {

    [superviewDidLoad];

    //设置返回不需要文字

    UIBarButtonItem *backButtonItem = [[UIBarButtonItemalloc]initWithTitle:@""style:UIBarButtonItemStylePlaintarget:nilaction:nil];

    [self.navigationItemsetBackBarButtonItem:backButtonItem];

}

第二种方法：黑盒子，利用运行时来替换viewDidLoad方法，即写一个分类，具体如下：

#import <UIKit/UIKit.h>
@interface UIViewController (EmptyBackButton)
@end
           

#import "UIViewController+EmptyBackButton.h"
#import <objc/runtime.h>

@implementation UIViewController (EmptyBackButton)

+ (void)load {
    staticdispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Class class = [selfclass];
        
        SEL originalSelector [email protected](viewDidLoad);
        SEL swizzledSelector [email protected](mob_viewDidLoad);
        
        Method originalMethod =class_getInstanceMethod(class, originalSelector);
        Method swizzledMethod =class_getInstanceMethod(class, swizzledSelector);
        
        BOOL didAddMethod =class_addMethod(class, originalSelector,method_getImplementation(swizzledMethod),method_getTypeEncoding(swizzledMethod));
        
        if (didAddMethod) {
            class_replaceMethod(class, swizzledSelector,method_getImplementation(originalMethod),method_getTypeEncoding(originalMethod));
        } else {
            method_exchangeImplementations(originalMethod, swizzledMethod);
        }
    });
}

- (void)mob_viewDidLoad {
    [selfmob_viewDidLoad];
    UIBarButtonItem *backButtonItem = [[UIBarButtonItemalloc]initWithTitle:@""style:UIBarButtonItemStylePlaintarget:nilaction:nil];
    [self.navigationItemsetBackBarButtonItem:backButtonItem];
}
           

参考链接：http://justabeech.com/2014/02/24/empty-back-button-on-ios7/