IOS 字符串字母大小写互转

有时候，后台返回的字符串全部是小写，而我们需要大写展示，又或者后台返回的字符串全部是大写，我们需要小写展示，怎么办？其实很简单，看代码

//小写转大写

-(NSString *)stringToUpper:(NSString *)str{

    for(NSInteger i =0 ; i < str.length ; i++){

        if([str characterAtIndex:i] >='a' &  [str characterAtIndex:i] <='z') {

            char temp = [str characterAtIndex:i] -32;

            NSRange range =NSMakeRange(i,1);

            str = [str stringByReplacingCharactersInRange:range withString:[NSString stringWithFormat:@"%c",temp]];

        }

    }

    return str;

}

//大写转小写

-(NSString *)stringToLower:(NSString *)str{

    for(NSInteger i = 0 ; i < str.length ; i++) {

        if([str characterAtIndex:i] >='A'& [str characterAtIndex:i] <='Z') {

            char temp = [str characterAtIndex:i]+32;

            NSRange range =NSMakeRange(i,1);

            str = [strs tringByReplacingCharactersInRange:range withString:[NSString stringWithFormat:@"%c",temp]];

        }

    }

    return str;

}

直接复制拿走用