所以我找到了可行的解决方案:

_logoutButton.titleLabel.text = NSLocalizedString(@"Logout",);
[_logoutButton setTitle:_logoutButton.titleLabel.text forState:UIControlStateNormal];

首先我们改变按钮的标题，然后调整这个标题的按钮大小

你实际上可以在动画块之外设置标题，只是要确保在performWithoutAnimation中调用layoutIfNeeded():

button1.setTitle("abc", forState: .Normal)
button2.setTitle("abc", forState: .Normal)
button3.setTitle("abc", forState: .Normal)
UIView.performWithoutAnimation {
    self.button1.layoutIfNeeded()
    self.button2.layoutIfNeeded()
    self.button3.layoutIfNeeded()
}

如果你有一堆按钮，考虑在超视图上调用layoutIfNeeded():

button1.setTitle("abc", forState: .Normal)
button2.setTitle("abc", forState: .Normal)
button3.setTitle("abc", forState: .Normal)
UIView.performWithoutAnimation {
    self.view.layoutIfNeeded()
}

使用performWithoutAnimation:方法，然后强制布局立即发生，而不是稍后。

[UIView performWithoutAnimation:^{
  [self.myButton setTitle:text forState:UIControlStateNormal];
  [self.myButton layoutIfNeeded];
}];

所以我找到了可行的解决方案:

_logoutButton.titleLabel.text = NSLocalizedString(@"Logout",);
[_logoutButton setTitle:_logoutButton.titleLabel.text forState:UIControlStateNormal];

首先我们改变按钮的标题，然后调整这个标题的按钮大小

我已经做了一个Swift扩展来做这个:

extension UIButton {
    func setTitleWithoutAnimation(title: String?) {
        UIView.setAnimationsEnabled(false)

        setTitle(title, forState: .Normal)

        layoutIfNeeded()
        UIView.setAnimationsEnabled(true)
    }
}

适用于我的iOS 8和9，与UIButtonTypeSystem。

(代码是Swift 2, Swift 3和Objective-C应该类似)

我得到了它的工作组合的答案:

[[[button titleLabel] layer] removeAllAnimations];

    [UIView performWithoutAnimation:^{

        [button setTitle:@"Title" forState:UIControlStateNormal];

    }];