嗨我有一个实现以前版本的iOS的单身如下:
.h文件
@interface CartSingleton : NSObject
{
}
+(CartSingleton *) getSingleton;
.m文件
@implementation CartSingleton
static CartSingleton *sharedSingleton = nil;
+(CartSingleton *) getSingleton
{
if (sharedSingleton !=nil)
{
NSLog(@"Cart has already been created.....");
return sharedSingleton;
}
@synchronized(self)
{
if (sharedSingleton == nil)
{
sharedSingleton = [[self alloc]init];
NSLog(@"Created a new Cart");
}
}
return sharedSingleton;
}
//==============================================================================
+(id)alloc
{
@synchronized([CartSingleton class])
{
NSLog(@"inside alloc");
NSAssert(sharedSingleton == nil, @"Attempted to allocate a second instance of a singleton.");
sharedSingleton = [super alloc];
return …我有一个UITableviewCell.当用户单击该单元格时,我保存索引路径,然后调用cellforrowAtIndexpath方法获取单元格,然后在该单元格上调用SetHighlighted:TRUE.
这工作正常,但问题是当我在桌面视图中上下滚动时,重新出现时所选单元格不会突出显示.如何使突出显示的蓝色颜色保持不变,这样即使向上或向下滚动表格,用户也可以直观地看到他们的选择？
谢谢
我一直在寻找并寻找这个答案.但是现在几个小时我似乎无法完成这项工作.请帮帮我.
我是我的rails应用程序的网页,我正在尝试显示保存在我的资源文件夹中的图像 @app/assets/images/rails.png.
我有一个javascript文件,其中包含构造html的以下函数.在这个函数里面,我想把链接传递给图像.这是我目前的代码.
function addToInfoWindow(infoWindowContent)
{
infoWindowString = '<div class="infoWindow">'+
**'<img src="/assets/images/rails.png" />'+**
'<p>'+infoWindowContent+'</p>'+
'<p><a href="http://www.google.com">See here</a></p>'+
'<p><a href="http://www.google.com">Upload a photo</a></p>'+
'</div>';
infoWindow.setContent(infoWindowString);
}
正如您在代码中看到的那样,粗体部分就是问题所在.我已经尝试了几种不同的url字符串组合来访问该图像文件,但图像没有显示在html元素中.
我看了看,尝试过rails帮助函数等image_url('rails.png').但我必须把它们放在错误的地方.有人可以帮帮我吗.请告诉我上面的代码中我需要添加什么函数来获取图像,/assets/images/rails.png以便将它的url放在上面突出显示的部分中,并在我的视图中显示.
我有这个表达式:
channelName = rhash["Channel"].gsub("'", " ")
它工作正常.但是,我只能用它替换1个字符.我想为替换添加一些字符.所以我尝试了以下方法:
channelName = rhash["Channel"].gsub(/[':;] /, " ")
这不起作用,即没有对字符串进行替换,也没有错误消息.我也试过这个:
channelName = rhash["Channel"].gsub!("'", " ")
这导致一个空白的字符串.所以绝对不是我想要的.
我想有一个gsub方法用我的字符串中的空格替换以下字符:
' ; :
我的问题:
如何构建我的gsub方法,以便用空格替换上述字符的所有实例？
gsub发生了什么事!以上为空白.
我是数据库编程的新手,我有一个非常基本的问题:
在我用于在我的数据库中创建表的PHPMyAdmin GUI中,当"type"(即.atatatype)列具有数据类型并且之后括号中的内容时,它意味着什么.例如:int(20),bigint(30).....
我理解int和bigint类型意味着使用的字节数,因此意味着可以存储的值的范围.但括号中的值是什么意思？
(20)和(30)代表什么......这对...有什么影响......
对不起,如果Q是基本的,我试图了解数据库....
非常感谢
我有这个文件:
app/views/listings/list.html.erb
在我的rails项目中.以下是该文件的内容:
<h1>This file is:"list.html.erb"</h1>
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<style type="text/css">
html { height: 100% }
body { height: 100%; margin: 0; padding: 0 }
#map_canvas { height: 100% }
</style>
<script type="text/javascript"
src="http://maps.googleapis.com/maps/api/js?key=key&sensor=false">
</script>
<%=javascript_include_tag 'application'%>
</head>
<body onload="initialize()">
<div id="map_canvas" style="width:80%; height:80%"</div>
<input type="button" onclick="getlistings();" value="Add Markers">
<input type="button" onclick="clearMarkers();" value="Remove Markers">
</body>
</html>
我喜欢将样式表应用于它.我应该在哪里放置样式表？我尝试将代码放在此文件中:
app/assets/stylesheets/listings.css.scss
但该样式未应用于html文件.我还需要更改我的html视图文件中的任何内容以包含样式表吗？
这是位于以下位置的样式表:"app/assets/stylesheets/listings.css.scss"
// Place all the styles related to the Listings controller here.
// They will …升级到Mountain Lion后,我遇到了很多关于Rails的麻烦.
到目前为止,我试图解决这些问题并在互联网上搜索几个小时我已经做了以下工作以确保我的系统在升级后具有运行rails的所有依赖关系:
ruby 1.9.2p290(2011-07-09修订版32553)[x86_64-darwin10.8.0]
我还发现Mountain Lion与Postgres有一些问题,所以我看到这篇文章,发现我需要将这一行添加到我的Bash配置文件中:
export PATH="/usr/local/bin:/usr/bin:$PATH"
现在我转到我升级之前在Snow Leopard上运行正常的Rails应用程序,当我rails s在命令行运行时出现以下错误:
AM@~/Documents/RailsWS/app0815 >gem install pg
Building native extensions. This could take a while...
ERROR: Error installing pg:
ERROR: Failed to build gem native extension.
/Users/AM/.rvm/rubies/ruby-1.9.2-p290/bin/ruby extconf.rb
checking for pg_config... yes
Using config values from /usr/bin/pg_config
checking for libpq-fe.h... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or …快速提问:
我有一个单例类,它注册了几个NSNotifications.因为Singletons持续超过应用程序的生命周期.
我必须实施吗？
[NSNotificationCenter defaultCenter] removeObserver:self]
在我的单身课程中？
什么是在iOS中与Singletons中的NSNotification中心打交道的正确方法？
谢谢
我试着按照一些关于在rails中注释我的模型的在线教程.然而,似乎所有的教程都在讨论过时的注释版本或不正确的安装它是一团糟.
到目前为止,我尝试了以下内容
1)在Gemfile中添加了这个
gem 'annotate', '2.4.0'
2)然后命令:
bundle install
3)然后我看到安装了注释gem并显示在命令上
bundle show
4)最后,为了注释我的模型,我使用了命令
bundle exec annotate --position before
在这一点上,我期待我的模型被注释,但我得到的是以下错误消息:
/Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.1/lib/active_record/railties/databases.rake:4:in `<top (required)>': undefined method `namespace' for main:Object (NoMethodError)
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.1/lib/active_record/railtie.rb:33:in `load'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.1/lib/active_record/railtie.rb:33:in `block in <class:Railtie>'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie.rb:184:in `instance_exec'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie.rb:184:in `block in load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie.rb:184:in `each'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie.rb:184:in `load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/engine.rb:423:in `block in load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/application/railties.rb:8:in `each'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/application/railties.rb:8:in `all'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/engine.rb:423:in `load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/application.rb:145:in `load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie/configurable.rb:30:in `method_missing'
from Rakefile:7:in `<top (required)>'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/annotate-2.4.0/lib/annotate.rb:17:in `load'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/annotate-2.4.0/lib/annotate.rb:17:in `load_tasks' …我有以下设置:
uploads_controller.rb:
class UploadsController < ApplicationController
before_action :set_upload, only: [:show, :edit, :update, :destroy]
# GET /uploads
def index
@uploads = Upload.all
update_file_status
@uploads = Upload.all
end
# GET /uploads/1
def show
end
# GET /uploads/new
def new
puts "Running uploads/new"
@upload = Upload.new()
end
# GET /uploads/1/edit
def edit
end
# POST /uploads
def create
@upload = Upload.new(upload_params)
if @upload.save
@upload.update!(:status => "1")
@upload.update!(:f_path => "#{@upload.sourcedata.path}")
redirect_to uploads_url, notice: "Upload for #{@upload.task.name} was successfully created with file #{@upload.sourcedata_file_name}."
else
redirect_to …javascript ajax ruby-on-rails unobtrusive-javascript actioncontroller
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