判断传入的字符串是否为空

- (BOOL)isBlankString:(NSString*)string

{

    if(string ==nil|| string ==NULL) {

        returnYES;

    }

    if ([string isKindOfClass:[NSNull class]]) {

        returnYES;

    }

    if ([[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]] length]==0) {

        returnYES;

    }

    if([stringisEqualToString:@"(null)"] || [stringisEqualToString:@"(NULL)"]) {

        returnYES;

    }

    return NO;

}