NSString字符串处理简单总结

1. 连接字符串
   Objective-C

   NSArray *strings = ... ; string = [strings componentsJoinedByString: @" :-) "]; // 结果：string1:-)string2:-)......

   1 2 3

   NSArray *strings = ... ; string = [strings componentsJoinedByString: @" :-) "]; // 结果：string1:-)string2:-)......

2. 分割字符串
   Objective-C

   NSString *string = @"string1:string2:string3:string4:string5"; NSArray *chunks = [string componentsSeparatedByString: @":"];

   1 2	NSString *string = @"string1:string2:string3:string4:string5"; NSArray *chunks = [string componentsSeparatedByString: @":"];

3. 转成数值
   Objective-C

   NSString *string = ...; int intValue = [string intValue]; // int数值 float floatValue = [string floatValue]; // float数值 double doubleValue = [string doubleValue]; // double数值

   1 2 3 4

   NSString *string = ...; int intValue = [string intValue]; // int数值 float floatValue = [string floatValue]; // float数值 double doubleValue = [string doubleValue]; // double数值

4. 从字符串中去除换行

   可以使用上面提到的分割字符串，然后再将它们连接起来。但是采用下面的方式更好一些。

   Objective-C

   NSMutableString *mstring = [NSMutableString stringWithString:string]; NSRange wholeShebang = NSMakeRange(0, [mstring length]); [mstring replaceOccurrencesOfString: @" " withString: @"" options: 0 range: wholeShebang];

   1 2 3 4 5 6 7 8

   NSMutableString *mstring = [NSMutableString stringWithString:string]; NSRange wholeShebang = NSMakeRange(0, [mstring length]); [mstring replaceOccurrencesOfString: @" " withString: @"" options: 0 range: wholeShebang];

   这个方法也可以用来替换字符串。这种方法比分割/连接字符串的方法稍微快一点儿，但不是很明显。处理长度1500000的字符串，当中有36909个换行，分割/连接的方法要0.124秒，这个方法要0.071秒。

5. 取得子字符串
   Objective-C

   NSRange range = [[string name] rangeOfString: otherString options: NSCaseInsensitiveSearch];

   1	NSRange range = [[string name] rangeOfString: otherString options: NSCaseInsensitiveSearch];

6. 取得当前日期的字符串

   通常将Date转化成NSString的方法是使用NSDateFormatter，但有时候可以使用特殊方法更简单的进行转化。比如想得到：“December 4, 2007”

   Objective-C

   [[NSDate date] descriptionWithCalendarFormat: @"%B %e, %Y" timeZone: nil locale: nil]

   1	[[NSDate date] descriptionWithCalendarFormat: @"%B %e, %Y" timeZone: nil locale: nil]

7. Trim一个NSString
   Objective-C

   NSString *ook = @"\n \t\t hello there \t\n \n\n"; NSString *trimmed = [ook stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]]; // 结果是hello there

   1 2 3 4 5

   NSString *ook = @"\n \t\t hello there \t\n \n\n"; NSString *trimmed = [ook stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]]; // 结果是hello there

8. 按行处理一个字符串

   如果一个本文文体，每一行是一条数据，想循环处理每一条数据要怎么做简单呢。看下面的例子：

   Objective-C

   NSMutableArray *altitudes = [NSMutableArray array]; NSString *altitudeString = [self altitudeStringFromGoogle: coords]; [altitudeString enumerateLinesUsingBlock: ^(NSString *line, BOOL *stop) { float value = [line floatValue]; [altitudes addObject: [NSNumber numberWithFloat: value]]; }];

   1 2 3 4 5 6 7

   NSMutableArray *altitudes = [NSMutableArray array]; NSString *altitudeString = [self altitudeStringFromGoogle: coords]; [altitudeString enumerateLinesUsingBlock: ^(NSString *line, BOOL *stop) { float value = [line floatValue]; [altitudes addObject: [NSNumber numberWithFloat: value]]; }];

9. 将字符串放在剪贴板上的方法
   Objective-C

   @implementation NSString (PasteboardGoodies) - (void) sendToPasteboard { [[NSPasteboard generalPasteboard] declareTypes: [NSArray arrayWithObject: NSStringPboardType] owner:nil]; [[NSPasteboard generalPasteboard] setString: self forType: NSStringPboardType]; } // sendToPasteboard @end // PasteboardGoodies

   1 2 3 4 5 6 7 8 9 10 11 12 13

   @implementation NSString (PasteboardGoodies) - (void) sendToPasteboard { [[NSPasteboard generalPasteboard] declareTypes: [NSArray arrayWithObject: NSStringPboardType] owner:nil]; [[NSPasteboard generalPasteboard] setString: self forType: NSStringPboardType]; } // sendToPasteboard @end // PasteboardGoodies