如何在iPhone中格式化SQLite日期？

Question

我知道SQLite不支持日期名稱和月份名稱。我已經通過this的問題。我爲它創建了兩個自定義函數。

我從天數轉換國慶節的名稱自定義函數：

(%w day of week 0-6 with sunday==0) 

代碼：

+(NSString*)dayNameStringFromDayNo:(NSString*)dayNo{ 
    return 
    ([dayNo isEqualToString:@"0"])?@"Sunday": 
    (([dayNo isEqualToString:@"1"])?@"Monday": 
    (([dayNo isEqualToString:@"2"])?@"Tuesday": 
     (([dayNo isEqualToString:@"3"])?@"Wednesday": 
     (([dayNo isEqualToString:@"4"])?@"Thursday": 
     (([dayNo isEqualToString:@"5"])?@"Friday": @"Saturday" 
     ) 
     ) 
    ) 
    ) 
    ); 
} 

我從本月爭取本月名稱的字符串自定義的方法：

(%m month: 01-12) 

代碼：

+(NSString*)monthNameFromNumber:(NSString*)no{ 
    return ([no isEqualToString:@"01"])?@"January": 
    (([no isEqualToString:@"02"])?@"February": 
    (([no isEqualToString:@"03"])?@"March": 
     (([no isEqualToString:@"04"])?@"April": 
     (([no isEqualToString:@"05"])?@"May": 
     (([no isEqualToString:@"06"])?@"June": 
     (([no isEqualToString:@"07"])?@"July": 
      (([no isEqualToString:@"08"])?@"August": 
      (([no isEqualToString:@"09"])?@"September": 
      (([no isEqualToString:@"10"])?@"October": 
      (([no isEqualToString:@"11"])?@"November":@"Decemeber" 
      ) 
      ) 
      )    
     ) 
     ) 
     ) 
     ) 
    ) 
    ) 
    ); 
} 

但對於日期格式如下

Sat 6th February 

如何得到這種輸出的？我是否必須再次爲它創建一個自定義函數？

Answer 1

你從SQLite獲得什麼日期格式？ SQLite沒有本地日期/時間數據類型，但通常將日期存儲爲格式爲YYYY-MM-DD HH:MM:SS的ISO8601字符串或Unix樣式的時間戳。

第1步：獲取日期作爲NSDate。這裏有一種方法，使用上述的ISO8601格式：

// Create a date formatter 
NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init]; 
[inputFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; 

// Use the formatter to convert the string you retrieved (from 
// SQLite) into an NSDate. 
NSDate *theDate = [inputFormatter dateFromString:yourSQLiteString]; 

// Don't forget to release alloc'ed resources 
[inputFormatter release]; 

如果你的約會被存儲爲一個Unix風格的時間戳，你可以跳過使用輸入格式，並使用NSDate dateWithTimeIntervalSince1970:代替。

第2步：轉換日期爲字符串：

// Create a date formatter for whatever format you want to output, 
// using the formatting patterns from Unicode tr35-6 Appendix F. 
outputFormatter = [[NSDateFormatter alloc] init]; 
[outputFormatter setDateFormat:@"EEE d MMMM"]; 
NSString *dateString = [dateFormatter stringFromDate:theDate]; 

// Don't forget to release alloc'ed resources. 
[outputFormatter release]; 

在這個例子中，你會得到一個字符串像Sat 6 February，假定用戶是在英語語言環境。

參考文獻：

• Data Formatting Programming Guide for Cocoa: Date Formatters
• Unicode Standard UTS #35: Appendix F: Date Format Patterns

Answer 2

爲什麼不使用formattion capabilities的客戶端代碼，或者ojective-c不包含strftime？

Answer 3

確定。我終於爲它添加了一些自定義方法。

+(NSString*)dayNameStringFromDayNo:(NSString*)dayNo{ 
    return 
    ([dayNo isEqualToString:@"0"])?@"Sunday": 
    (([dayNo isEqualToString:@"1"])?@"Monday": 
    (([dayNo isEqualToString:@"2"])?@"Tuesday": 
     (([dayNo isEqualToString:@"3"])?@"Wednesday": 
     (([dayNo isEqualToString:@"4"])?@"Thursday": 
     (([dayNo isEqualToString:@"5"])?@"Friday": @"Saturday" 
     ) 
     ) 
     ) 
    ) 
    ); 
} 

+(NSString*)dayNameHalfStringFromDayNo:(NSString*)dayNo{ 
    return 
    ([dayNo isEqualToString:@"0"])?@"Sun": 
    (([dayNo isEqualToString:@"1"])?@"Mon": 
    (([dayNo isEqualToString:@"2"])?@"Tues": 
     (([dayNo isEqualToString:@"3"])?@"Wed": 
     (([dayNo isEqualToString:@"4"])?@"Thu": 
     (([dayNo isEqualToString:@"5"])?@"Fri": @"Sat" 
     ) 
     ) 
     ) 
    ) 
    ); 
} 

+(NSString*)monthNameFromNumber:(NSString*)no{ 
    return ([no isEqualToString:@"01"])?@"January": 
    (([no isEqualToString:@"02"])?@"February": 
    (([no isEqualToString:@"03"])?@"March": 
     (([no isEqualToString:@"04"])?@"April": 
     (([no isEqualToString:@"05"])?@"May": 
     (([no isEqualToString:@"06"])?@"June": 
     (([no isEqualToString:@"07"])?@"July": 
      (([no isEqualToString:@"08"])?@"August": 
      (([no isEqualToString:@"09"])?@"September": 
      (([no isEqualToString:@"10"])?@"October": 
      (([no isEqualToString:@"11"])?@"November":@"Decemeber" 
      ) 
      ) 
      )    
      ) 
     ) 
     ) 
     ) 
     ) 
    ) 
    ); 
} 


+(NSString*)monthNameHalfFromNumber:(NSString*)no{ 
    return ([no isEqualToString:@"01"])?@"Jan": 
    (([no isEqualToString:@"02"])?@"Feb": 
    (([no isEqualToString:@"03"])?@"Mar": 
     (([no isEqualToString:@"04"])?@"Apr": 
     (([no isEqualToString:@"05"])?@"May": 
     (([no isEqualToString:@"06"])?@"Jun": 
     (([no isEqualToString:@"07"])?@"Jul": 
      (([no isEqualToString:@"08"])?@"Aug": 
      (([no isEqualToString:@"09"])?@"Sep": 
      (([no isEqualToString:@"10"])?@"Oct": 
      (([no isEqualToString:@"11"])?@"Nov":@"Dec" 
      ) 
      ) 
      )    
      ) 
     ) 
     ) 
     ) 
     ) 
    ) 
    ); 
} 

+(NSString*)suffixNameForNumber:(NSString*)no{ 
    NSInteger noV=[no intValue]; 
    if(noV>=11 && noV<=20){ 
     return [no stringByAppendingString:@"th"]; 
    } else { 
     NSString *l=[no substringFromIndex:1]; 
     if([l isEqualToString:@"1"]){ 
      return [no stringByAppendingString:@"st"]; 
     } else if([l isEqualToString:@"2"]){ 
      return [no stringByAppendingString:@"nd"]; 
     } else if([l isEqualToString:@"3"]){ 
      return [no stringByAppendingString:@"rd"]; 
     } else { 
      return [no stringByAppendingString:@"th"]; 
     } 
    } 
}