问按钮和自动布局

EN

@interface ViewController ()
@property (strong,nonatomic) NSMutableDictionary *viewsDict;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.viewsDict = [NSMutableDictionary dictionary];
    for (int i=1; i<7; i++) {
        UIButton *b = [UIButton buttonWithType:UIButtonTypeRoundedRect];
        [b setTitle:[NSString stringWithFormat:@"Button%d",i] forState:UIControlStateNormal];
        [b setTranslatesAutoresizingMaskIntoConstraints:NO];
        [self.viewsDict setObject:b forKey:[NSString stringWithFormat:@"b%d",i]];
        [self.view addSubview:b];
    }

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|[b1][b2(==b1)]|" options:0 metrics:nil views:self.viewsDict]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|[b3][b4(==b3)]|" options:0 metrics:nil views:self.viewsDict]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|[b5][b6(==b5)]|" options:0 metrics:nil views:self.viewsDict]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[b1][b3(==b1)][b5(==b1)]|" options:0 metrics:nil views:self.viewsDict]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[b2][b4(==b2)][b6(==b2)]|" options:0 metrics:nil views:self.viewsDict]];
}