改变字符串的大小写
NSString *string1 = @"A String";
NSString *string2 = @"string hu";
NSLog(@"string1:%@",[string1 uppercaseString]);//uppercaseString返回转换为大写的字符串
NSLog(@"string2:%@",[string2 lowercaseString]);//lowercaseString返回转换为小写的字符串
NSLog(@"string2:%@",[string2 capitalizedString]);//capitalizedString返回每个单词首字母大写的字符串
2012-11-04 15:46:48.203 Untitled[30998:707] string1:A STRING
2012-11-04 15:46:48.205 Untitled[30998:707] string2:string hu
2012-11-04 15:46:48.205 Untitled[30998:707] string2:String Hu