MFMailComposeViewController上取消并发送按钮丢失iOS

Question

我正在iOS应用程序，用户可以通过电子邮件发送短信。我正在使用MFMailComposeViewController & MFMessageComposeViewController用于发送电子邮件和短信，但有时取消和发送按钮显示在作曲家身上，有时它不会根本不出现。这个问题是随机的，我已经尝试了很多想法。任何帮助将不胜感激。 代码

MFMailComposeViewController *mail = [[MFMailComposeViewController alloc] init]; 
    mail.mailComposeDelegate = self; 
    [mail setSubject:Email_Subject]; 
    [mail setMessageBody:Share_Message isHTML:NO]; 
    [mail setToRecipients:@[@""]]; 
    [self presentViewController:mail animated:YES completion:NULL]; 

我已经在我的头文件中的viewController实施MFMailComposeViewControllerDelegate。

Answer 1

好的，我终于得到了一些牵引力。我的问题部分来自梗在我的应用程序委托（SWIFT）改变导航栏的颜色：

UINavigationBar.appearance().barTintColor = UIColor.black 
    UIApplication.shared.statusBarStyle = .lightContent 

    // To get my hamburger menu white colored 
    UINavigationBar.appearance().tintColor = UIColor.white 

由于这一点，并与缩放模式的一些互动（见上面我的意见），有时我会得到取消/发送按钮在我的邮件控制器中设置为白色。就像这样：

我会告诉你我的课（目标C）显示的邮件控制器，它现在的作品对我来说，这个问题解决问题。需要注意的是该行：

[UINavigationBar appearance].tintColor = appleBlueTintColor; 

真的是在这一切的秘密武器：

#import <MessageUI/MessageUI.h> 

@interface SendEmail : MFMailComposeViewController 

// Returns nil if can't send email on this device. Displays an alert before returning in this case. 
- (id) initWithParentViewController: (UIViewController *) parent; 

// Show the email composer. 
- (void) show; 

// Message to append to the bottom of support emails. The string doesn't contain HTML. 
+ (NSString *) getVersionDetailsFor: (NSString *) appName; 

@end 

@interface SendEmail()<MFMailComposeViewControllerDelegate> 
@property (nonatomic, weak) UIViewController *myParent; 
@property (nonatomic, strong) UIColor *previousBarTintColor; 
@property (nonatomic, strong) UIColor *previousTintColor; 
@end 

#import "SendEmail.h" 
#import <sys/utsname.h> 
@implementation SendEmail 

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
{ 
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
    if (self) { 
     // Custom initialization 
    } 
    return self; 
} 

// Using this init method depends on the `show` method being called immediately after-- to reset the nav bar colors back to what they were originally. 
- (id) initWithParentViewController: (UIViewController *) theParent { 
    if (![MFMailComposeViewController canSendMail]) { 
     NSString *title = @"Sorry, the app isn't allowed to send email."; 
     NSString *message = @"Have you configured this device to send email?"; 
     UIAlertController *alert = [UIAlertController alertControllerWithTitle:title message:message preferredStyle:UIAlertControllerStyleAlert]; 
     [alert addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil]]; 
     [theParent presentViewController:alert animated:YES completion:nil]; 
     return nil; 
    } 

    // The default app nav bar color is black-- and that looks bad on the mail VC. Need to change and then set back both the barTintColor and the tintColor (in the `show` method). 

    self.previousBarTintColor = [UINavigationBar appearance].barTintColor; 
    self.previousTintColor = [UINavigationBar appearance].tintColor; 

    [[UINavigationBar appearance] setBarTintColor:[UIColor whiteColor]]; 

    // I got this color from the digital color meter-- this is what it is supposed to be on the Cancel/Send buttons. 
    UIColor *appleBlueTintColor = [UIColor colorWithRed:31.0/255.0 green:134.0/255.0 blue:254.0/255.0 alpha:1.0]; 
    [UINavigationBar appearance].tintColor = appleBlueTintColor; 

    self = [super init]; 
    if (self) { 
     self.mailComposeDelegate = self; 
     self.myParent = theParent; 
    } 

    return self; 
} 

- (void) show { 
    [self.myParent presentViewController:self animated:YES completion:^{ 
     [[UINavigationBar appearance] setBarTintColor: self.previousBarTintColor]; 
     [UINavigationBar appearance].tintColor = self.previousTintColor; 
    }]; 
} 

- (void)mailComposeController:(MFMailComposeViewController*)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError*)error { 
    [self.myParent dismissViewControllerAnimated:YES completion:nil]; 
} 

+ (NSString *) getVersionDetailsFor: (NSString *) appName; 
{ 
    NSMutableString *message = [NSMutableString string]; 
    [message appendString:@"\n\n\n--------------\n"]; 
    [message appendFormat:@"iOS version: %@\n", [[UIDevice currentDevice] systemVersion]]; 
    [message appendFormat:@"%@ version: %@ (%@)\n", appName, 
    [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"], 
    [[NSBundle mainBundle]objectForInfoDictionaryKey:@"CFBundleVersion"]]; 
    [message appendFormat:@"Hardware: %@\n", [self machineName]]; 

    return message; 
} 

// See http://stackoverflow.com/questions/11197509/ios-iphone-get-device-model-and-make 
+ (NSString *) machineName; 
{ 
    struct utsname systemInfo; 
    uname(&systemInfo); 

    return [NSString stringWithCString:systemInfo.machine 
           encoding:NSUTF8StringEncoding]; 
} 

@end