iOS 显示警报控制器对象

Question

我有更多页面将显示 UIAlertController。

所以我需要将警报代码写在一个方法中，class写在一页中。

我想使用 class 并调用方法可以在任何 Viewcontroller 上显示警报。

如何在 class.

中编写 presentviewcontroller

我的头文件如下：

 #import <Foundation/Foundation.h>
 #import "VisionAPI.h"

 @interface VisionAPI : NSObject

 +(void) showMessageAlert:(NSString *) title andMessage:(NSString*) msg andDoneMsg:(NSString*) done;

 @end

我的工具文件如下：

 #import "VisionAPI.h"
 #import <UIKit/UIKit.h>
 @implementation VisionAPI

 +(void) showMessageAlert:(NSString *) title andMessage:(NSString*) msg andDoneMsg:(NSString*) done{

     UIAlertController *showMsgAlertController = [UIAlertController alertControllerWithTitle: title message: msg preferredStyle: UIAlertControllerStyleAlert];
UIAlertAction *showMsgAlertControllerOkAction = [UIAlertAction actionWithTitle:done  style:UIAlertActionStyleDefault
                                                       handler:nil];
       [showMsgAlertController addAction:showMsgAlertControllerOkAction];
dispatch_async(dispatch_get_main_queue(), ^{

       [self presentViewController:showMsgAlertController animated:YES completion:nil];
     });
 }
 @end

但是上面的代码会在这一行显示错误：

 [self presentViewController:showMsgAlertController animated:YES completion:nil];

如何在NSObject中呈现ViewController，或者如何解决问题。

Answer 1

Add view controller as a parameter argument in your function and pass the 'self' (instance/object of view controller) from which view controller, you want to present your alert controller.

+(void) showMessageAlert:(NSString *) title andMessage:(NSString*) msg andDoneMsg:(NSString*) done fromViewController: (UIViewController)viewController{

     UIAlertController *showMsgAlertController = [UIAlertController alertControllerWithTitle: title message: msg preferredStyle: UIAlertControllerStyleAlert];
UIAlertAction *showMsgAlertControllerOkAction = [UIAlertAction actionWithTitle:done  style:UIAlertActionStyleDefault
                                                       handler:nil];
       [showMsgAlertController addAction:showMsgAlertControllerOkAction];
dispatch_async(dispatch_get_main_queue(), ^{

       [viewController presentViewController:showMsgAlertController animated:YES completion:nil];
     });
 }
 @end

如果您不想每次都将视图控制器作为此函数的参数参数传递，您也可以使用应用程序的根视图控制器。如下：

+(void) showMessageAlert:(NSString *) title andMessage:(NSString*) msg andDoneMsg:(NSString*) done{

         UIAlertController *showMsgAlertController = [UIAlertController alertControllerWithTitle: title message: msg preferredStyle: UIAlertControllerStyleAlert];
    UIAlertAction *showMsgAlertControllerOkAction = [UIAlertAction actionWithTitle:done  style:UIAlertActionStyleDefault
                                                           handler:nil];
           [showMsgAlertController addAction:showMsgAlertControllerOkAction];
    dispatch_async(dispatch_get_main_queue(), ^{

RootViewController *rootController = (RootViewController*)[[(AppDelegate*)
                                   [[UIApplication sharedApplication]delegate] window] rootViewController];

           [rootController presentViewController:showMsgAlertController animated:YES completion:nil];
         });
     }
@end

Answer 2

你可以在NSObject中得到最顶层的view controller，如下图：

- (UIViewController*)topMostController
        {
            UIViewController *topController = [self rootViewController];

            while ([topController presentedViewController]) topController = [topController presentedViewController];

            //  Returning topMost ViewController
            return topController;
        }


+(void) showMessageAlert:(NSString *) title andMessage:(NSString*) msg andDoneMsg:(NSString*) done{

         UIAlertController *showMsgAlertController = [UIAlertController alertControllerWithTitle: title message: msg preferredStyle: UIAlertControllerStyleAlert];
    UIAlertAction *showMsgAlertControllerOkAction = [UIAlertAction actionWithTitle:done  style:UIAlertActionStyleDefault
                                                           handler:nil];
           [showMsgAlertController addAction:showMsgAlertControllerOkAction];
    dispatch_async(dispatch_get_main_queue(), ^{

           [[self topMostController] presentViewController:showMsgAlertController animated:YES completion:nil];
         });
     }

iOS 显示警报控制器对象

iOS show alert controller object

xcode

objective-c

ios

swift

uialertcontroller