UILabelで幅固定で高さを計算する

gistfile1.m

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, 50.0, 500.0)];
view.translatesAutoresizingMaskIntoConstraints = NO;
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0.0, 0.0, 50.0, 44.0)];
label.translatesAutoresizingMaskIntoConstraints = NO;
label.lineBreakMode = NSLineBreakByWordWrapping;
[label setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical];
[label setContentCompressionResistancePriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisVertical];
label.text = @"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
label.numberOfLines = 0;
NSLog(@"%@", NSStringFromCGRect(label.frame));
[view addSubview:label];
[view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[label]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(label)]];
[view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[label]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(label)]];
[label addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[label(200@300)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(label)]];
[view layoutIfNeeded];
NSLog(@"%@", NSStringFromCGRect(label.frame));