如何调用系统发送信息？

• 第一种方法
  使用MFMessageComposeViewController系统的邮箱系统来发送信息

添加库：

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引入头文件：

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代码：

#import "ViewController.h"
#import <MessageUI/MessageUI.h>

// 遵守代理
@interface ViewController ()<MFMailComposeViewControllerDelegate,MFMessageComposeViewControllerDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    // 启动信息模块
    if ([MFMessageComposeViewController canSendText]) {
        MFMessageComposeViewController *messageComposer =
        [[MFMessageComposeViewController alloc] init];
        NSString *message = @"Message!!!";
        [messageComposer setBody:message];
        messageComposer.messageComposeDelegate = self;
        [self presentViewController:messageComposer animated:YES completion:nil];
    }
}

// 处理发送结果
- (void)messageComposeViewController:(MFMessageComposeViewController *)controller didFinishWithResult:(MessageComposeResult)result{
    
    ///your stuff here
    
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end```

- 第二种方法

[[UIApplication sharedApplication]openURL:[NSURL URLWithString:@"sms:MobileNumber"]];```