IOS7 实现 Apple 解决覆盖文本域的键盘问题

Question

虽然这个问题已经在很多场合被描述过，但我在参考和 IOS7 和 Apple 提出的解决方案的上下文中提出了这个问题，该解决方案在此处的文档中有所描述：

https://developer.apple.com/library/ios/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/KeyboardManagement/KeyboardManagement.html

问题：键盘覆盖了文本视图。解决方案：使用苹果建议的方法，将观察者附加到键盘事件，将 UIScrollView uo 滚动到键盘高度。

我已经创建了单个 texfield 的简单实现，它是视图控制器中滚动视图的子视图，确保视图控制器是两者的代表，并确保调用正确的方法。

TestViewController.h

#import <UIKit/UIKit.h>

@interface TestViewController : UIViewController <UITextFieldDelegate, UIScrollViewDelegate>

@end

TestViewController.m

#import "TestViewController.h"

@interface TestViewController ()
@property (weak, nonatomic) IBOutlet UITextField *testTextField;
@property (weak, nonatomic) IBOutlet UIScrollView *scrollView;


@end

@implementation TestViewController

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

    [self registerForKeyboardNotifications];
}

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

- (void)registerForKeyboardNotifications
{
    NSLog(@"registerForKeyboardNotifications got called");


    [[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
{
    NSLog(@"keyboardWasShown got called");

    NSDictionary* info = [aNotification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;

    UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0);
    self.scrollView.contentInset = contentInsets;
    self.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, self.testTextField.frame.origin) ) {
        [self.scrollView scrollRectToVisible:self.testTextField.frame animated:YES];
    }
}

// Called when the UIKeyboardWillHideNotification is sent
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{

    NSLog(@"keyboardWillBeHidden got called");

    UIEdgeInsets contentInsets = UIEdgeInsetsZero;
    self.scrollView.contentInset = contentInsets;
    self.scrollView.scrollIndicatorInsets = contentInsets;
}

- (BOOL) textFieldShouldReturn:(UITextField *)textField
{

    [textField resignFirstResponder];
    return TRUE;
}



@end

Answer 1

我已经使用 Swift 编辑了 Apple 解决方案。

import UIKit

class ExampleViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet var scrollView: UIScrollView!

    @IBOutlet var textField1: UITextField!
    @IBOutlet var textField2: UITextField!
    @IBOutlet var textField3: UITextField!
    @IBOutlet var textField4: UITextField!
    @IBOutlet var textField5: UITextField!

    var activeTextField: UITextField!

    // MARK: - View
    override func viewDidLoad() {
        super.viewDidLoad()
        self.textField1.delegate = self
        self.textField2.delegate = self
        self.textField3.delegate = self
        self.textField4.delegate = self
        self.textField5.delegate = self
    }

    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
        self.registerForKeyboardNotifications()
    }

    override func viewWillDisappear(animated: Bool) {
        super.viewWillDisappear(animated)
        self.unregisterFromKeyboardNotifications()
    }

    // MARK: - Keyboard

    // Call this method somewhere in your view controller setup code.
    func registerForKeyboardNotifications() {
        let center:  NSNotificationCenter = NSNotificationCenter.defaultCenter()
        center.addObserver(self, selector: "keyboardWasShown:", name: UIKeyboardDidShowNotification, object: nil)
        center.addObserver(self, selector: "keyboardWillBeHidden:", name: UIKeyboardWillHideNotification, object: nil)
    }

    func unregisterFromKeyboardNotifications () {
        let center:  NSNotificationCenter = NSNotificationCenter.defaultCenter()
        center.removeObserver(self, name: UIKeyboardDidShowNotification, object: nil)
        center.removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
    }

    // Called when the UIKeyboardDidShowNotification is sent.
    func keyboardWasShown (notification: NSNotification) {
        let info : NSDictionary = notification.userInfo!
        let kbSize = (info.objectForKey(UIKeyboardFrameBeginUserInfoKey)?.CGRectValue as CGRect!).size

        let contentInsets: UIEdgeInsets = 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.
        var aRect = self.view.frame
        aRect.size.height -= kbSize.height;
        if (!CGRectContainsPoint(aRect, self.activeTextField.frame.origin) ) {
            self.scrollView.scrollRectToVisible(self.activeTextField.frame, animated: true)
        }
    }

    // Called when the UIKeyboardWillHideNotification is sent
    func keyboardWillBeHidden (notification: NSNotification) {
        let contentInsets = UIEdgeInsetsZero;
        scrollView.contentInset = contentInsets;
        scrollView.scrollIndicatorInsets = contentInsets;
    }

    // MARK: -  Text Field

    func textFieldDidBeginEditing(textField: UITextField) {
        self.activeTextField = textField
    }

    func textFieldDidEndEditing(textField: UITextField) {
        self.activeTextField = nil
    }

}