AutoLayoutStandardViewController.m

#import "AutoLayoutStandardViewController.h"

@interface AutoLayoutStandardViewController ()
@property (strong, nonatomic) NSLayoutConstraint *constraintToAnimate;
@property (strong, nonatomic) UILabel *label;
- (void)animateLabel;
@end

@implementation AutoLayoutStandardViewController

- (void)loadView
{
    CGRect applicationFrame = [[UIScreen mainScreen] applicationFrame];
    UIView *mainView = [[UIView alloc] initWithFrame:applicationFrame];
    mainView.backgroundColor = [UIColor whiteColor];
    self.view = mainView;
    
    self.label = [UILabel new];
    self.label.text = @"This is a Label";
    self.label.font = [UIFont systemFontOfSize:18];
    self.label.backgroundColor = [UIColor lightGrayColor];
    self.label.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:self.label];
    

    self.constraintToAnimate = [NSLayoutConstraint constraintWithItem:self.label
                                                            attribute:NSLayoutAttributeTop
                                                            relatedBy:NSLayoutRelationEqual
                                                               toItem:self.view
                                                            attribute:NSLayoutAttributeBottom
                                                           multiplier:0.25
                                                             constant:0.0];
     [self.view addConstraint:self.constraintToAnimate];
     
     [self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.label
                                                           attribute:NSLayoutAttributeCenterX
                                                           relatedBy:NSLayoutRelationEqual
                                                              toItem:self.view
                                                           attribute:NSLayoutAttributeCenterX
                                                          multiplier:1.0
                                                            constant:0.0]];
    
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self performSelector:@selector(animateLabel) withObject:nil afterDelay:2.0];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

- (void)animateLabel {
    [self.view removeConstraint:self.constraintToAnimate];
    self.constraintToAnimate = [NSLayoutConstraint constraintWithItem:self.label
                                                            attribute:NSLayoutAttributeTop
                                                            relatedBy:NSLayoutRelationEqual
                                                               toItem:self.view
                                                            attribute:NSLayoutAttributeBottom
                                                           multiplier:0.5
                                                             constant:0.0];
    [self.view addConstraint:self.constraintToAnimate];
    [UIView animateWithDuration:0.5 animations:^{
        [self.view layoutIfNeeded];
    }];
}

@end