小编8vi*_*ius的帖子

我正在做SaaS Stanford课程,试图完成这项任务的第5部分

我很难掌握这个概念,这就是我试图做的事情:

class Class
  def attr_accessor_with_history(attr_name)
    attr_name = attr_name.to_s
    attr_reader attr_name
    attr_reader attr_name + '_history'
    class_eval %Q'{def #{attr_name}(a);#{attr_name}_history.push(a) ; end;}'
  end
end

我可能会做各种各样的错误,阅读关于元编程的The Book of Ruby章节,我仍然没有得到它,有人能帮我理解这个吗？

我有一个需要播放声音的运动应用程序.我使用AVAudioPlayer播放声音.但是当音频开始播放时,来自另一个应用程序(无线电流应用程序)的背景音乐将被关闭.

如何让它不中断背景音乐？因为我希望用户在锻炼时听到音乐.

谢谢.

我正在尝试使用FFMPEG将AMR音频文件转换为MP3.我在Windows 7主机上使用VBox运行Ubuntu 10.10并且我已经安装了ffmpeg运行sudo apt-get install ffmpeg我已经有一个我以前记录过的AMR文件所以我运行了命令:ffmpeg -i myfile.amr myfile.mp3转换失败,跟踪如下:

FFmpeg version 0.6-4:0.6-2ubuntu6, Copyright (c) 2000-2010 the FFmpeg developers
  built on Oct  5 2010 22:35:47 with gcc 4.4.5
  configuration: --extra-version=4:0.6-2ubuntu6 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --enable-shared --disable-static
  WARNING: library configuration mismatch
  libavutil   configuration: --extra-version=4:0.6-2ubuntu6 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc …

我试图通过改变颜色来自定义我的按钮,但当我使用时:

self.loginButton.layer.backgroundColor = [UIColor colorWithRed:0.0 green:157.0/255.0 blue:223.0/255.0 alpha:1.0].CGColor;

要么

self.loginButton.backgroundColor = [UIColor colorWithRed:0.0 green:157.0/255.0 blue:223.0/255.0 alpha:1.0];

我得到的就是这个结果:

我想要做的是将白色改为蓝色,任何想法我做错了什么？

我正在使用Rails 4枚举,我想正确测试它们,所以我为枚举字段设置了这些测试:

it { should validate_inclusion_of(:category).in_array(%w[sale sale_with_tax fees lease tax_free other payroll]) }
it { should validate_inclusion_of(:type).in_array(%w[receivable payable]) }

这是他们正在验证的模型:

class Invoice < ActiveRecord::Base
  belongs_to :user

  enum category: [:sale, :sale_with_tax, :fees, :lease, :tax_free, :other, :payroll]
  enum type: [:receivable, :payable]

  validates :user, presence: true
  validates :issue_date, presence: true
  validates :series, presence: true
  validates :folio, presence: true
  validates :issuing_location, presence: true
  validates :payment_method, presence: true
  validates :last_digits, presence: true
  validates :credit_note, presence: true
  validates :total, presence: true
  validates :subtotal, presence: true
  validates …

我需要向用户显示我的应用中的帖子日期,现在我以这种格式显示:"5月25日星期五".如何格式化NSDate以读取"2小时前"的内容？使其更加用户友好.

如何在BS3中检查Tag元素是否属于某种类型,例如a div？

我的应用程序中有一个UIWebView,问题是我有一个UIAppearance来修改分段控件的外观,因此它修改了UIWebView文本字段的输入附件视图中的分段控件,我希望它看起来不错,或者不试图修改它.这是它目前的样子:

我在运行bundler安装我的宝石时收到此错误.我环顾四周找不到解决办法,除了在rvm上安装openssl pkg并重新安装所有红宝石,这样做没有解决问题,还有其他可能的解决方案吗？

这是我运行bundle install的输出:

Fetching gem metadata from https://rubygems.org/.Unfortunately, a fatal error has occurred. Please see the Bundler 
troubleshooting documentation at http://bit.ly/bundler-issues. Thanks! 
/home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': /home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/x86_64-linux/openssl.so: undefined symbol: SSLv2_method - /home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/x86_64-linux/openssl.so (LoadError)
    from /home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from /home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/openssl.rb:17:in `<top (required)>'
    from /home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from /home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from /home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/net/https.rb:22:in `<top (required)>'
    from /home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from /home/octavius/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from /home/octavius/.rvm/gems/ruby-1.9.3-p125@global/gems/bundler-1.2.1/lib/bundler/vendor/net/http/persistent.rb:447:in `ssl'
    from /home/octavius/.rvm/gems/ruby-1.9.3-p125@global/gems/bundler-1.2.1/lib/bundler/vendor/net/http/persistent.rb:216:in `connection_for'
    from /home/octavius/.rvm/gems/ruby-1.9.3-p125@global/gems/bundler-1.2.1/lib/bundler/vendor/net/http/persistent.rb:358:in `request'
    from /home/octavius/.rvm/gems/ruby-1.9.3-p125@global/gems/bundler-1.2.1/lib/bundler/fetcher.rb:149:in `fetch'
    from /home/octavius/.rvm/gems/ruby-1.9.3-p125@global/gems/bundler-1.2.1/lib/bundler/fetcher.rb:177:in `fetch_dependency_remote_specs'
    from /home/octavius/.rvm/gems/ruby-1.9.3-p125@global/gems/bundler-1.2.1/lib/bundler/fetcher.rb:135:in `fetch_remote_specs'
    from /home/octavius/.rvm/gems/ruby-1.9.3-p125@global/gems/bundler-1.2.1/lib/bundler/fetcher.rb:73:in `specs'
    from /home/octavius/.rvm/gems/ruby-1.9.3-p125@global/gems/bundler-1.2.1/lib/bundler/source.rb:234:in `block in …

我的UI中有一个文本字段,当它被选中时会显示UIDatePicker而不是默认键盘,如何设置一个按钮,以便在用户完成时关闭选择器？