Objective-c NSMutableString 可變字串

NSString本身不允許修改內容及字串的長度，如果要修改的話，可以使用NSMutableString。

NSMutableString是NSString的子類，所以，所有NSString的方法都適用於NSMutableString。

NSString *str1 = @"Welcome,same!";NSString *str2,*str3;NSMutableString *mstr;NSRange range;mstr = [NSMutableString stringWithString:str1];NSLog(@"%@",mstr);[mstr insertString:@"back " atIndex:9];NSLog(@"%@",mstr);[mstr insertString:@"How are you" atIndex:[mstr length]];NSLog(@"%@",mstr);[mstr appendString:@" in there?"];NSLog(@"%@",mstr);[mstr deleteCharactersInRange:NSMakeRange(29,9)];NSLog(@"%@",mstr);range = [mstr rangeOfString:@"How are you?"];if(range.location != NSNotFound){   [mstr deleteCharactersInRange:range];   NSLog(@"%@",mstr);}[mstr setString:@"Welcome,Sam!"];NSLog(@"%@",mstr);

運行結果：

Welocome,Sam!
Welocome,back Sam!
Welocome,back Sam!How are you
Welocome,back Sam!How are you in there?
Welocome,back Sam!How are you?
Welocome,back Sam!