iOS - 通知监听键盘高度

#define   SINGLE_NOTICE   [NSNotificationCenter defaultCenter]

#import "ViewController.h"

@interface
ViewController ()<UITextFieldDelegate> {

    float
_keyboardHeight; //
键盘高度

    UITextField *_currentTF;
// 当前正在编辑的输入框

}

@end

@implementation ViewController

- (void)viewDidAppear:(BOOL)animated {

    [super
viewDidAppear:animated];

    [SINGLE_NOTICE
addObserver:self
selector:@selector(keyBoardWillShown:)
name:UIKeyboardWillChangeFrameNotification
object:nil];

}

- (void)viewDidDisappear:(BOOL)animated {

    [super
viewDidDisappear:animated];

    [SINGLE_NOTICE
removeObserver:self
name:UIKeyboardWillChangeFrameNotification
object:nil];

}

- (void)viewDidLoad {

    [super
viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    self.view.backgroundColor
= [UIColor whiteColor];

    

    for (NSInteger i =
0; i<2; i++) {

       
// 方便对比，创建两个输入框

        UITextField *tf = [[UITextField
alloc] init];

        tf.frame =
CGRectMake(50,
500-300*i,
200, 40);

        tf.backgroundColor = [UIColor
lightGrayColor];

        tf.placeholder =
@"input your info at this...";

        tf.delegate =
self;

        tf.returnKeyType =
UIReturnKeyDone;

        [tf setValue:[UIColor
redColor]
forKeyPath:@"_placeholderLabel.textColor"];

        [self.view
addSubview:tf];

    }

}

#pragma mark - 通知方法

- (void)keyBoardWillShown:(NSNotification *)noti {

    NSDictionary *info = [noti
userInfo];

    NSValue *value = [info
objectForKey:UIKeyboardFrameBeginUserInfoKey];

    CGRect keyboardRect = [value
CGRectValue];

    if (_keyboardHeight ==
0.000000) {

        _keyboardHeight = keyboardRect.size.height;

        [self
makeTFVisible];

    }

//    NSLog(@"keyHeight===%f",_keyboardHeight);

    _keyboardHeight = keyboardRect.size.height;

}

- (void)makeTFVisible {

    float textFieldUpHeight =
_keyboardHeight - (self.view.frame.size.height
- (_currentTF.frame.size.height+_currentTF.frame.origin.y));

    if (textFieldUpHeight >
0) {

        [UIView
animateWithDuration:0.25
animations:^{

            self.view.frame =
CGRectMake(0, -textFieldUpHeight,
self.view.frame.size.width,
self.view.frame.size.height);

        }];

    }

}

#pragma mark - 输入框代理方法 -

- (void)textFieldDidBeginEditing:(UITextField *)textField {

    _currentTF = textField;

    if (_keyboardHeight !=
0.000000) {

        [self
makeTFVisible];

    }

}

- (void)textFieldDidEndEditing:(UITextField *)textField {

    [UIView
animateWithDuration:0.25
animations:^{

        self.view.frame
= CGRectMake(0,
0, self.view.frame.size.width,
self.view.frame.size.height);

    }];

}

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

    if (textField.returnKeyType ==
UIReturnKeyDone) {

        [textField resignFirstResponder];

    }

    return
YES;

}

- (void)touchesBegan:(NSSet<UITouch *> *)touches
withEvent:(UIEvent *)event {

    [self.view
endEditing:YES];

}