iOS键盘自适应弹出效果

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
<UITextFieldDelegate>


@end

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.
  
  
  UITextField *field=[[UITextField alloc]initWithFrame:CGRectMake(100, 300, 50, 50)];
  field.backgroundColor=[UIColor redColor];
  field.delegate=self;
  [self.view addSubview:field];
  
  
  
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
  
}
#pragma -mark -keyboard notificatin
- (void)keyboardWillShow:(NSNotification *)notification {
  NSDictionary *info = [notification userInfo];
  // keyboardHeight 为键盘高度
  CGSize keyboardSize = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
  [self animateViewWithKeyboardHeight:keyboardSize.height];
}

- (void)keyboardWillHide:(NSNotification *)notification {
  [self animateViewWithKeyboardHeight:0.0];
}

- (void)animateViewWithKeyboardHeight:(CGFloat)keyboardHeight {
  NSTimeInterval animationDuration = 0.3f;
  CGFloat height = self.view.bounds.size.height;
  CGFloat width = self.view.bounds.size.width;
  CGFloat topSize = 0.0;
  CGFloat viewH = self.view.frame.size.height-64;
  CGFloat deviceHeight = [UIScreen mainScreen].bounds.size.height;
  CGFloat animateH = deviceHeight - viewH - keyboardHeight;
  if (animateH >= 0) {
    topSize = 0;
    CGRect toRect = CGRectMake(0, topSize, width, height);
    self.view.frame = toRect;
    
  } else {
    topSize = animateH;
    CGRect toRect = CGRectMake(0, topSize, width, height);
    [UIView animateWithDuration:animationDuration animations:^{
      self.view.frame = toRect;
    }];
  }
}
#pragma -mark -UITextFieldDelegate
-(BOOL)textFieldShouldReturn:(UITextField *)textField
{
  [textField resignFirstResponder];
  
  return YES;
}

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


@end