AutoLayoutのコード設定を覚えるのが面倒なので備忘録。
今回は中央配置。
ex:UILabelを中央配置

//UILabelの作成
UILabel *centerLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 100, 20)];
centerLabel.text = @"centerLabel";

//autoresizingMaskをoff
[centerLabel setTranslatesAutoresizingMaskIntoConstraints:NO];

//水平値の制約
NSLayoutConstraint *xConstraint = [NSLayoutConstraint constraintWithItem:centerLabel
                                                               attribute:NSLayoutAttributeCenterX
                                                               relatedBy:NSLayoutRelationEqual
                                                                  toItem:self.view
                                                               attribute:NSLayoutAttributeCenterX
                                                              multiplier:1
                                                                constant:0];

//垂直値の制約
NSLayoutConstraint *yConstraint = [NSLayoutConstraint constraintWithItem:centerLabel
                                                               attribute:NSLayoutAttributeCenterY
                                                               relatedBy:NSLayoutRelationEqual
                                                                  toItem:self.view
                                                               attribute:NSLayoutAttributeCenterY
                                                              multiplier:1
                                                                constant:0];

[self.view addSubview:centerLabel];
[self.view addConstraint:xConstraint];
[self.view addConstraint:yConstraint];