iosUITextField属性

@property UITextField *caption;

caption = [[UITextField alloc] initWithFrame:CGRectMake(0,

                                                            self.frame.size.height/2,

                                                            self.frame.size.width,

                                                            32)];

    caption.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5];

    caption.textAlignment = NSTextAlignmentCenter;

    caption.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;

    caption.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;

    caption.textColor = [UIColor whiteColor];

    caption.keyboardAppearance = UIKeyboardAppearanceDark;

    caption.alpha = 0;

    caption.tintColor = [UIColor whiteColor];

    caption.delegate = self;