IOS

CenterScrollView

-(void)setContentOffset:(CGPoint)contentOffset
{
    const CGSize contentSize = self.contentSize;
    const CGSize scrollViewSize = self.bounds.size;
    //automatically center scrollview content when the scroll size is within bounds
    if (contentSize.width + self.contentInset.left + self.contentInset.right < scrollViewSize.width) {
        contentOffset.x = - (scrollViewSize.width - contentSize.width) / 2.0;
    }
    if (contentSize.height + self.contentInset.top + self.contentInset.bottom < scrollViewSize.height) {
        contentOffset.y = - (scrollViewSize.height - contentSize.height) / 2.0;
    }
    
    [super setContentOffset:contentOffset];
}

KeyboardManagement

#import "ViewController.h"
#import "UIResponder+FirstResponder.h"
#import "PXScrollView.h"
@interface ViewController ()

@property (weak, nonatomic) IBOutlet PXScrollView *scrollView;
@property(nonatomic, weak) UIView *activeTextInput;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasShown:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
}

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


#pragma mark - KeyboardManagement
- (void)keyboardWasShown:(NSNotification *)notification
{
    NSDictionary *userInfo = [notification userInfo];
    
    CGSize kbSize = [[userInfo objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    
    UIEdgeInsets contentInset = UIEdgeInsetsMake(0, 0, kbSize.height, 0);
    self.scrollView.contentInset = contentInset;
    self.scrollView.scrollIndicatorInsets = contentInset;
    CGRect scrollViewRect = self.scrollView.frame;
    scrollViewRect.size.height -= kbSize.height;
    
    id textInputView = [UIResponder getFirstResponder];
    
    if ([textInputView isKindOfClass:[UITextField class]]
        ||
        [textInputView isKindOfClass:[UITextView class]]) {
        if (!CGRectContainsPoint(scrollViewRect, ((UIView *)textInputView).frame.origin)) {
            [self.scrollView scrollRectToVisible:((UIView *)textInputView).frame animated:YES];
        }
    }
    
}

- (void)keyboardWillHide:(NSNotification *)notification
{
    UIEdgeInsets contentInset = UIEdgeInsetsZero;
    self.scrollView.contentInset = contentInset;
    self.scrollView.scrollIndicatorInsets = contentInset;
}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    id firstResponder = [UIResponder getFirstResponder];
    if ([firstResponder isKindOfClass:[UITextField class]] || [firstResponder isKindOfClass:[UITextView class]]) {
        UITouch *touch = [touches anyObject];
        if ([firstResponder isFirstResponder] && touch.view != firstResponder) {
            [firstResponder resignFirstResponder];
        }
    }
}

UIResponder+FirstResponder.m

static __weak id _currentFirstResponder;
static BOOL _shouldAutomaticallyDismissKeyboard;

@implementation UIResponder (FirstResponder)

+(id)getFirstResponder
{
    _currentFirstResponder = nil;
    
    [[UIApplication sharedApplication] sendAction:@selector(populateFirstResponder) to:nil from:nil forEvent:nil];
    return _currentFirstResponder;
}

- (void)populateFirstResponder
{
    _currentFirstResponder = self;
}