Facebook Paper Login

PaperLoginViewController.m

#import "PaperLoginViewController.h"

@interface PaperLoginViewController() <UITextFieldDelegate>
@property (strong, nonatomic) UILabel *titleLabel;
@property (strong, nonatomic) UITextField *usernameField;
@property (strong, nonatomic) UITextField *passwordField;
@property (strong, nonatomic) UIView *separator;

@property (strong, nonatomic) NSMutableArray *keyboardShownConstraints;
@property (strong, nonatomic) NSMutableArray *keyboardHiddenConstraints;
@end

@implementation PaperLoginViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    UIColor *transparentWhite = [UIColor colorWithWhite:1.0 alpha:0.5];
    
    _titleLabel = [[UILabel alloc] initWithFrame:CGRectZero];
    _titleLabel.translatesAutoresizingMaskIntoConstraints = NO;
    _titleLabel.text = @"Login";
    _titleLabel.font = [UIFont fontWithName:@"AvenirNext-UltraLight" size:60.0f];
    _titleLabel.textColor = [UIColor whiteColor];
    [_titleLabel sizeToFit];
    [self.view addSubview:_titleLabel];
    
    _usernameField = [[UITextField alloc] initWithFrame:CGRectZero];
    _usernameField.delegate = self;
    _usernameField.translatesAutoresizingMaskIntoConstraints = NO;
    _usernameField.textColor = [UIColor whiteColor];
    _usernameField.tintColor = [UIColor whiteColor];
    _usernameField.font = [UIFont fontWithName:@"AvenirNext-UltraLight" size:30.0f];
    _usernameField.enablesReturnKeyAutomatically = YES;
    _usernameField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:@"Username"
                                                                           attributes:@{NSForegroundColorAttributeName: transparentWhite}];
    [_usernameField setKeyboardType:UIKeyboardTypeEmailAddress];
    [_usernameField setReturnKeyType:UIReturnKeyNext];
    [self.view addSubview:_usernameField];

    _passwordField = [[UITextField alloc] initWithFrame:CGRectZero];
    _passwordField.delegate = self;
    _passwordField.translatesAutoresizingMaskIntoConstraints = NO;
    _passwordField.textColor = [UIColor whiteColor];
    _passwordField.tintColor = [UIColor whiteColor];
    _passwordField.font = [UIFont fontWithName:@"AvenirNext-UltraLight" size:30.0f];
    _passwordField.secureTextEntry = YES;
    _passwordField.enablesReturnKeyAutomatically = YES;
    _passwordField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:@"Password"
                                                                           attributes:@{NSForegroundColorAttributeName: transparentWhite}];
    [_passwordField setKeyboardType:UIKeyboardTypeDefault];
    [_passwordField setReturnKeyType:UIReturnKeyGo];
    [self.view addSubview:_passwordField];
    
    _separator = [[UIView alloc] initWithFrame:CGRectZero];
    _separator.translatesAutoresizingMaskIntoConstraints = NO;
    _separator.backgroundColor = transparentWhite;
    [self.view addSubview:_separator];
    
    NSDictionary *views = @{
        @"title": _titleLabel,
        @"username": _usernameField,
        @"password": _passwordField,
        @"separator": _separator
    };
    
    NSLayoutConstraint *titleCenter = [NSLayoutConstraint constraintWithItem:_titleLabel
                                                                   attribute:NSLayoutAttributeCenterX
                                                                   relatedBy:NSLayoutRelationEqual
                                                                      toItem:self.view
                                                                   attribute:NSLayoutAttributeCenterX
                                                                  multiplier:1.0 constant:0.0f];

    NSArray *verticalConstraints = [NSLayoutConstraint
                    constraintsWithVisualFormat:@"V:|-top-[title]-space-[username]-(8)-[separator(1)]-(8)-[password]"
                                               options:kNilOptions
                                               metrics:@{
                                                         @"top": @(120),
                                                         @"space": @(100)
                                                         }
                                               views:views];

    NSArray *usernameHorizontalConstraints = [NSLayoutConstraint
                                    constraintsWithVisualFormat:@"H:|-[username]-|"
                                    options:kNilOptions
                                    metrics:nil
                                    views:views];

    NSArray *separatorHorizontalConstraints = [NSLayoutConstraint
                                              constraintsWithVisualFormat:@"H:|-[separator]-|"
                                              options:kNilOptions
                                              metrics:nil
                                              views:views];
    
    NSArray *passwordHorizontalConstraints = [NSLayoutConstraint
                                              constraintsWithVisualFormat:@"H:|-[password]-|"
                                              options:kNilOptions
                                              metrics:nil
                                              views:views];
    
    _keyboardHiddenConstraints = [NSMutableArray array];
    [_keyboardHiddenConstraints addObject:titleCenter];
    [_keyboardHiddenConstraints addObjectsFromArray:verticalConstraints];
    [_keyboardHiddenConstraints addObjectsFromArray:usernameHorizontalConstraints];
    [_keyboardHiddenConstraints addObjectsFromArray:separatorHorizontalConstraints];
    [_keyboardHiddenConstraints addObjectsFromArray:passwordHorizontalConstraints];
    
    verticalConstraints = [NSLayoutConstraint
        constraintsWithVisualFormat:@"V:|-top-[title]-space-[username]-(8)-[separator(1)]-(8)-[password]"
                           options:kNilOptions
                           metrics:@{
                                     @"top": @(70),
                                     @"space": @(40)
                                     }
                           views:views];

    _keyboardShownConstraints = [NSMutableArray array];
    [_keyboardShownConstraints addObject:titleCenter];
    [_keyboardShownConstraints addObjectsFromArray:verticalConstraints];
    [_keyboardShownConstraints addObjectsFromArray:usernameHorizontalConstraints];
    [_keyboardShownConstraints addObjectsFromArray:separatorHorizontalConstraints];
    [_keyboardShownConstraints addObjectsFromArray:passwordHorizontalConstraints];
    
    [self.view addConstraints:_keyboardHiddenConstraints];
    
    UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc]
                                             initWithTarget:self action:@selector(respondToTapGesture:)];
    tapRecognizer.numberOfTapsRequired = 1;
    [self.view addGestureRecognizer:tapRecognizer];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
}

- (BOOL)prefersStatusBarHidden {
    return YES;
}

#pragma mark - UITextFieldDelegate
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    if (textField == _usernameField) {
        [_passwordField becomeFirstResponder];
    } else if (textField == _passwordField) {
        [_passwordField resignFirstResponder];
        
        // TODO: Should go ahead with login
    }
    
    return YES;
}

#pragma mark - Tap Gesture callback

- (void)respondToTapGesture:(id)obj {
    [_usernameField resignFirstResponder];
    [_passwordField resignFirstResponder];
}

#pragma mark - Keyboard callbacks

- (void)keyboardWillShow:(NSNotification *)notification {
    [self.view removeConstraints:_keyboardHiddenConstraints];
    [self.view addConstraints:_keyboardShownConstraints];
    [UIView animateWithDuration:0.3f animations:^{
        [self.view layoutIfNeeded];
    }];
}

- (void)keyboardWillHide:(NSNotification *)notification {
    [self.view removeConstraints:_keyboardShownConstraints];
    [self.view addConstraints:_keyboardHiddenConstraints];
    [UIView animateWithDuration:0.3f animations:^{
        [self.view layoutIfNeeded];
    }];
}

@end