UITextFieldDelegate适用于iOS 8,但不适用于iOS 7

我有一个UIViewController,其中包含UITextField,并且符合UITextFieldDelegate协议。当我第一次构建应用程序时,iOS 7是最新的iOS,当我选择文本字段时,键盘就会出现,正如预期的那样。

iOS 8和Xcode 6也随之而来。自从我第一次编写代码以来,代码没有任何变化,但奇怪的是,现在当我在iOS 8设备上选择文本字段时,键盘会出现,但在iOS 7设备上却没有。

为什么会这样?有什么想法吗?

这是我的代码:

#import "BBFeatVC.h"

@interface BBFeatVC ()

@end

@implementation BBFeatVC

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

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.featTextField.delegate = self;

    // Set label
    self.featLabel.numberOfLines = 0;

    // enhance keypad
    UIToolbar* numberToolbar = [[UIToolbar alloc]initWithFrame:CGRectMake(0, 0, 320, 50)];
    numberToolbar.barStyle = UIBarStyleBlackTranslucent;
    numberToolbar.items = [NSArray arrayWithObjects:
                           [[UIBarButtonItem alloc]initWithTitle:@"Cancel" style:UIBarButtonItemStyleBordered target:self action:@selector(cancelNumberPad)],
                           [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil],
                           [[UIBarButtonItem alloc]initWithTitle:@"Apply" style:UIBarButtonItemStyleDone target:self action:@selector(doneWithNumberPad)],
                           nil];
    [numberToolbar sizeToFit];
    self.featTextField.inputAccessoryView = numberToolbar;

}

-(void)cancelNumberPad{
    [self.featTextField resignFirstResponder];
}

-(void)doneWithNumberPad{

    NSString *numberFromTheKeyboard = self.featTextField.text;
    NSNumberFormatter *f = [[NSNumberFormatter alloc] init];
    [f setNumberStyle:NSNumberFormatterDecimalStyle];
    NSNumber *num = [f numberFromString:numberFromTheKeyboard];

    NSInteger newStat = [num integerValue];
    [[NSUserDefaults standardUserDefaults] setInteger:newStat forKey:self.featStat];
    [self.featTextField resignFirstResponder];
}

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

@end