数组和字符串是否有值（是否为空） 判断

if (array != nil && ![array isKindOfClass:[NSNull class]] && array.count != 0)

 2 判断字符串

- (BOOL) isBlankString:(NSString *)string
{
    if (string == nil || string == NULL) {
        return YES;
    }
    if ([string isKindOfClass:[NSNull class]]) {
        return YES;
    }
    if ([[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]] length]==0) {
        return YES;
    }
    return NO;
}