March 11th, 2014
昨天把NSDate的一些處理稍微研究了一下，有一些處理方式可以整理一下:
1. 比較時間 (NSDate comparison)
<code style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;font-family:Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;white-space:inherit;"><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#00008b;" class="kwd">if</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">([</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pln">date1 compare</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">:</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pln">date2</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">]</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">==</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#2b91af;" class="typ">NSOrderedDescending</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">)<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">{<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#2b91af;" class="typ"> NSLog</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">(@</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#800000;" class="str">"date1 is later than date2"</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">);<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">}<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#00008b;" class="kwd">else</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#00008b;" class="kwd">if</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">([</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pln">date1 compare</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">:</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pln">date2</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">]</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">==</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#2b91af;" class="typ">NSOrderedAscending</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">)<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">{<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#2b91af;" class="typ"> NSLog</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">(@</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#800000;" class="str">"date1 is earlier than date2"</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">);<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">}<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#00008b;" class="kwd">else</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">{<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#2b91af;" class="typ"> NSLog</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">(@</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;color:#800000;" class="str">"dates are the same"</span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">);<br></br></span><span style="margin:0;padding:0;border:0;font-size:13.63636302948px;vertical-align:baseline;background-color:transparent;" class="pun">}</span></code>
可以拿來比較時間的先後，在NSDate大概算是最方便的．
參考: http://stackoverflow.com/questions/5965044/how-to-compare-two-nsdates-which-is-more-recent
**
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2. 時區的轉換
使用NSDate拿來的時間都是GMT要顯示的時候得轉成當地時區(台灣是TST)
-(NSString) transferGMT2TST: (NSDate)inGMT :(NSString*) newTZ
{
NSDateFormatter *dateFormatter = [[NSDateFormatteralloc] init];
dateFormatter.dateFormat = @”yyyy-MM-dd’T’HH:mm”;
NSTimeZone *nTZ = [NSTimeZonetimeZoneWithAbbreviation:newTZ];
[dateFormatter setTimeZone:nTZ];
return [dateFormatter stringFromDate:inGMT];
}
- 也可以把NSDate當成一個時間比對或是timer，可以先設定一個未來的時間，然後做時間的比較．
繼續研究….