iOS空值判断

+ (NSString *)pal_excludeNil:(NSString *)str{
    
    if ([str isKindOfClass:[NSString class]]) {
        if (str !=nil &&
            ![str isEqualToString:@"(null)"] &&
            ![str isEqualToString:@""] &&
            ![str isEqualToString:@"<null>"]){
            return str;
        }else{
            return @"";
        }
    }else if([str isKindOfClass:[NSNumber class]]){
        return [NSString stringWithFormat:@"%@",str];
    }else{
        return @"";
    }
}

+ (BOOL)isValidOfDictionary:(NSDictionary *)dictionary
{
    if (!dictionary || [dictionary isKindOfClass:[NSNull class]] || ![dictionary isKindOfClass:[NSDictionary class]] || dictionary.count <= 0) {
        return NO;
    };
    return YES;
}