[[UIApplication sharedApplication]openURL:[NSURL URLWithString:@"sms:number"]] 

这将是最好和最简单的方法。

//Add the Framework in .h file

#import <MessageUI/MessageUI.h>
#import <MessageUI/MFMailComposeViewController.h>

//Set the delegate methods

UIViewController<UINavigationControllerDelegate,MFMessageComposeViewControllerDelegate>

//add the below code in .m file


- (void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];

    MFMessageComposeViewController *controller = 
    [[[MFMessageComposeViewController alloc] init] autorelease];

    if([MFMessageComposeViewController canSendText])
    { 
        NSString *str= @"Hello";
        controller.body = str;
        controller.recipients = [NSArray arrayWithObjects:
                                 @"", nil];
        controller.delegate = self;
        [self presentModalViewController:controller animated:YES];  
    }


}

- (void)messageComposeViewController:
(MFMessageComposeViewController *)controller
                 didFinishWithResult:(MessageComposeResult)result 
{
    switch (result)
    {
        case MessageComposeResultCancelled:  
            NSLog(@"Cancelled");    
            break; 
        case MessageComposeResultFailed:
            NSLog(@"Failed");
            break;   
        case MessageComposeResultSent:      
            break; 
        default:  
            break;  
    }  
    [self dismissModalViewControllerAnimated:YES]; 
}

You must add the MessageUI.framework to your Xcode project Include an #import <MessageUI/MessageUI.h> in your header file Add these delegates to your header file MFMessageComposeViewControllerDelegate & UINavigationControllerDelegate In your IBAction method declare instance of MFMessageComposeViewController say messageInstance To check whether your device can send text use [MFMessageComposeViewController canSendText] in an if condition, it'll return Yes/No In the if condition do these: First set body for your messageInstance as: messageInstance.body = @"Hello from Shah"; Then decide the recipients for the message as: messageInstance.recipients = [NSArray arrayWithObjects:@"12345678", @"87654321", nil]; Set a delegate to your messageInstance as: messageInstance.messageComposeDelegate = self; In the last line do this: [self presentModalViewController:messageInstance animated:YES];

添加MessageUI。框架并使用下面的代码

#import <MessageUI/MessageUI.h> 

然后:

if ([MFMessageComposeViewController canSendText]) {
  MFMessageComposeViewController *messageComposer =
  [[MFMessageComposeViewController alloc] init];
  NSString *message = @"Your Message here";
  [messageComposer setBody:message];
  messageComposer.messageComposeDelegate = self;
  [self presentViewController:messageComposer animated:YES completion:nil];
}

以及委托方法-

- (void)messageComposeViewController:(MFMessageComposeViewController *)controller
             didFinishWithResult:(MessageComposeResult)result {
      [self dismissViewControllerAnimated:YES completion:nil];
 }

你可以展示MFMessageComposeViewController，它可以发送短信，但是有用户提示(他点击发送按钮)。没有用户许可，不可能这样做。在iOS 11上，你可以做扩展，就像传入消息的过滤器，告诉iOS它是不是垃圾邮件。没有什么是短信不能做的

这是一个教程，它完全是你正在寻找的:MFMessageComposeViewController。

http://blog.mugunthkumar.com/coding/iphone-tutorial-how-to-send-in-app-sms/

从本质上讲:

MFMessageComposeViewController *controller = [[[MFMessageComposeViewController alloc] init] autorelease];
if([MFMessageComposeViewController canSendText])
{
    controller.body = @"SMS message here";
    controller.recipients = [NSArray arrayWithObjects:@"1(234)567-8910", nil];
    controller.messageComposeDelegate = self;
    [self presentModalViewController:controller animated:YES];
}

还有文档的链接。

https://developer.apple.com/documentation/messageui/mfmessagecomposeviewcontroller