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

Swift 4版Xhacker刘回答

import Foundation
import UIKit
extension UIButton {
    func setTitleWithOutAnimation(title: String?) {
        UIView.setAnimationsEnabled(false)

        setTitle(title, for: .normal)

        layoutIfNeeded()
        UIView.setAnimationsEnabled(true)
    }
} 

从iOS 7.1开始，唯一适合我的解决方案是用UIButtonTypeCustom类型初始化按钮。

请注意:

当_button的"buttonType"为"UIButtonTypeSystem"时，以下代码无效:

[UIView setAnimationsEnabled:NO];
[_button setTitle:@"title" forState:UIControlStateNormal];
[UIView setAnimationsEnabled:YES];

当_button的"buttonType"为"UIButtonTypeCustom"时，上述代码有效。

一个方便的扩展动画按钮标题变化在Swift，发挥与默认实现很好:

import UIKit

extension UIButton {
  /// By default iOS animated the title change, which is not desirable in reusable views
  func setTitle(_ title: String?, for controlState: UIControlState, animated: Bool = true) {
    if animated {
      setTitle(title, for: controlState)
    } else {
      UIView.setAnimationsEnabled(false)
      setTitle(title, for: controlState)
      layoutIfNeeded()
      UIView.setAnimationsEnabled(true)
    }
  }
}

斯威夫特5

myButton.titleLabel?.text = "title"
myButton.setTitle("title", for: .normal)