October 2011
1 post
1 tag
Perform a Block after Delay
- (void)performBlock:(void (^)(void))block afterDelay:(NSTimeInterval)delay
{
int64_t delta = (int64_t)(1.0e9 * delay);
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, delta),
dispatch_get_main_queue(), block);
}
Then, we use:
[self performBlock: ^{
//Lines of code in block to execute
} afterDelay: 0.5f];
August 2011
1 post
1 tag
Setting to nil
NSObject *obj;
if (obj != nil) {
//code will enter here and we'll get a bad access error to obj!
}
vs.
NSObject *obj = nil;
if (obj != nil) {
//obj is nil so we're safe if we do something with obj
}
February 2011
1 post
2 tags
Hex String to Color (ARGB)
public Color HexStringToColor(string hex)
{
hex = hex.Replace("#", "").ToLowerInvariant();
if (hex.Length == 6)
{
hex = "ff" + hex;
}
else if (hex.Length != 8)
{
throw new Exception(hex + "
is not a valid 6 or 8-place
hexadecimal color code.");
}
int a, r, g, b;
a = Convert.ToInt32(hex.Substring(0, 2), 16);
r = Convert.ToInt32(hex.Substring(2, 2), 16);
g =...
July 2010
1 post
1 tag
Swapping variable values using multiple assignment...
Lua allows multiple assignment, where a list of values is assigned to a list of variables in one step. Both lists have their elements separated by commas. For instance, in the assignment
a, b = 10, 2*x
the variable a gets the value 10 and b gets 2*x.
In a multiple assignment, Lua first evaluates all values and only then executes the assignments. Therefore, we can use a multiple assignment...
April 2010
1 post
2 tags
NSDate to DateTime and Back
Reference Date is January 1, 2001 0:00:00 UTC (GMT)
It’s important to note the Local Time Zone vs. UTC/GMT
NSDate to DateTime
public static DateTime NSDateToDateTime(NSDate date)
{
DateTime reference = TimeZone.CurrentTimeZone.ToLocalTime(
new DateTime(2001, 1, 1, 0, 0, 0) );
return reference.AddSeconds(date.SecondsSinceReferenceDate);
}
DateTime to NSDate
public...
February 2010
3 posts
3 tags
Strip HTML Tags
using System.Text.RegularExpressions;
...
public static string StripHTML(string htmlText)
{
return Regex.Replace(htmlText, "<(.|\n)*?>", "");
}
“Always code as if the guy who ends up maintaining your code will be a violent...”
– Martin Golding (?)
2 tags
Unicode Date Format Patterns →
January 2010
2 posts
3 tags
Integer to Ordinal
public string AddOrdinal(int num)
{
switch(num % 100)
{
case 11:
case 12:
case 13:
return num.ToString() + "th";
}
switch(num % 10)
{
case 1:
return num.ToString() + "st";
case 2:
return num.ToString() + "nd";
case 3:
return num.ToString() + "rd";
default:
return...
1 tag
age from birthday
Rather than dividing figures by a fixed number days (which ignores special cases like leap years), I find this method quite reliable.
//Given DateTime birthday
TimeSpan span = DateTime.Now - birthday;
DateTime time = DateTime.MinValue + span;
int age = time.Year - 1;
August 2009
2 posts
1 tag
“Any fool can write code that a computer can understand. Good programmers write...”
– Martin Fowler
1 tag
System.IO.Path.Combine Behavior
When using Path.Combine, you should be aware of the behavior that if the second parameter has a leading slash, it will ignore the first parameter.
Given the following:
string root = "c:\"; string path = "test.txt"; string lead = "\test.txt";
We get the following results:
using System.IO;
… Path.Combine(root, path); // ‘c:\test.txt’ Path.combine(root, lead); ...
June 2009
2 posts
1 tag
3 A's Pattern For Writing Test Methods
Arrange, Act, Assert. Specifically, use separate code paragraphs (groups of lines of code separated by a blank line) for each of the As. Arrange is variable declaration and initialization. Act is invoking the code under test. Assert is using the Assert.* methods to verify that expectations were met. Following this pattern consistently makes it easy to revisit test code.
[source: Principles...
1 tag
HTTP GET for ASP.NET Webservices
It’s disabled by default and to enable it, add this to the web.config
<configuration>
<system.web>
<webServices>
<protocols>
<add name="HttpGet"/>
<add name="HttpPost"/>
</protocols>
</webServices>
</system.web>
</configuration>
Alternatively, you can enable these protocols...
May 2009
3 posts
1 tag
Safe Casting
Use the as keyword.
MyClass castedObject = obj as MyClass;
This won’t throw a class cast exception. Instead, castedObject will return null if obj isn’t a MyClass.
1 tag
Chain ?? Operators
You can use multiple ?? operators to chain multiple null comparisons:
string text = value1 ?? value2 ?? String.Empty;
1 tag
Normalizing & Comparing Strings
When normalizing strings, it is highly recommended that you use ToUpperInvariant instead of ToLowerInvariant because Microsoft has optimized the code for performing uppercase comparisons.
[source: CLR via C# ]