当键盘在文本字段上时,ios移动scrollview

我尝试使用来自ios开发人员库https://developer.apple.com/library/ios/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/KeyboardManagement/KeyboardManagement.html的代码实现它

但我不知道他们的意思是“活动字段存储在自定义变量中(在本例中称为activeField)”并且我可能做了其他错误.在viewWillAppear中使用registerForKeyboardNotifications是好的吗？

我知道有一些关于这个问题的线索,但我是新手,我很难理解它们.而且我不想只是学习如何,但为什么,这就是为什么我不想使用github其他建议等的现成的解决方案.

我的代码atm：

.H：

#import <UIKit/UIKit.h>

@interface VNViewController : UIViewController<uiscrollviewdelegate,UITextFieldDelegate>

@property (weak,nonatomic) IBOutlet UITextField *texticek;
@property (strong,nonatomic) IBOutlet UIScrollView *scrollView;

@end

.M：

#import "VNViewController.h"

@interface VNViewController ()

@end


@implementation VNViewController

@synthesize scrollView;
@synthesize texticek;

- (void) viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [self registerForKeyboardNotifications];
}

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

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // dispose of any resources that can be recreated.
}
// Call this method somewhere in your view controller setup code.
- (void)registerForKeyboardNotifications
{
    [[NSNotificationCenter defaultCenter] addobserver:self
                                             selector:@selector(keyboardWasShown:)
                                                 name:UIKeyboardDidShowNotification object:nil];

    [[NSNotificationCenter defaultCenter] addobserver:self
                                         selector:@selector(keyboardWillBeHidden:)
                                             name:UIKeyboardWillHideNotification object:nil];

}

// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
    NSDictionary* info = [aNotification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;

    UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0,0.0,kbSize.height,0.0);
    scrollView.contentInset = contentInsets;
    scrollView.scrollIndicatorInsets = contentInsets;

    // If active text field is hidden by keyboard,scroll it so it's visible
    // Your app might not need or want this behavior.
    CGRect aRect = self.view.frame;
    aRect.size.height -= kbSize.height;
    if (!CGRectContainsPoint(aRect,activeField.frame.origin) ) {
        [self.scrollView scrollRectToVisible:activeField.frame animated:YES];
    }
}

// Called when the UIKeyboardWillHideNotification is sent
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
    UIEdgeInsets contentInsets = UIEdgeInsetsZero;
    scrollView.contentInset = contentInsets;
    scrollView.scrollIndicatorInsets = contentInsets;
}

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    activeField = textField;
}

- (void)textFieldDidEndEditing:(UITextField *)textField
{
    activeField = nil;
}

@end