#import 
    
     - (void)viewDidLoad {    [super viewDidLoad];    self.view.backgroundColor = [UIColor whiteColor];        // 利用runtime来替换展现弹出框的方法    static dispatch_once_t onceToken;    dispatch_once(&onceToken, ^{        Method presentM = class_getInstanceMethod(self.class, @selector(presentViewController:animated:completion:));        Method presentSwizzlingM = class_getInstanceMethod(self.class, @selector(ox_presentViewController:animated:completion:));        // 交换方法实现        method_exchangeImplementations(presentM, presentSwizzlingM);    });}// 自己的替换展示弹出框的方法- (void)ox_presentViewController:(UIViewController *)viewControllerToPresent animated:(BOOL)flag completion:(void (^)(void))completion {        if ([viewControllerToPresent isKindOfClass:[UIAlertController class]]) {// 要弹出的是UIAlertController        // 输出到控制到可以发现两者都是null        NSLog(@"title : %@",((UIAlertController *)viewControllerToPresent).title);        NSLog(@"message : %@",((UIAlertController *)viewControllerToPresent).message);                // 换图标时的提示框的title和message都是nil，由此可特殊处理        UIAlertController *alertController = (UIAlertController *)viewControllerToPresent;        if (alertController.title == nil && alertController.message == nil) {// 是换图标的提示            return;        } else {// 其他提示还是正常处理            [self ox_presentViewController:viewControllerToPresent animated:flag completion:completion];            return;        }    }        // 其他的弹出还是正常处理    [self ox_presentViewController:viewControllerToPresent animated:flag completion:completion];}复制代码