将原字符串进行小写转大写，大写转小写

Objective-c

/*
 //将原字符串进行小写转大写，大写转小写
 //比如输入 @"aBCdEfGA" 输出 @"AbcDeFga"
 +(NSString *)reveserChacter:(NSString*)srcStr;
 */
int main()
{
    NSString *str = @"aBCdEfGA" ;
    char ch;
    NSMutableString *str1 = [NSMutableString string];
    for (int i=0; i<str.length; i++) {
        ch = [str characterAtIndex:i];
        if (ch>='a'&&ch<='z') {
            ch=ch-32;
            [str1 appendFormat:@"%c",ch];
        }
        else
        {
            ch = ch+32;
            [str1 appendFormat:@"%c",ch];
        }
    }
    NSLog(@"%@",str);
    NSLog(@"%@",str1);
}