2019-01-07iOS 判断数组、字符串、字典是否为（nil/空指针/空）

//判断数组
if(self.dataArray != nil && ![self.dataArray isKindOfClass:[NSNull class]] && self.dataArray.count != 0){
}

//判断字典 
NSDictionary *dict =self.datas[indexPath.row];
    if([[dict allKeys] containsObject:@"key"]){
        cell.textLabel.text= [dict valueForKey:@"key"];
    }else{
        cell.textLabel.text=@"没有对应的key值";
    }
//判断字符串
if ( string == nil || string == NULL || [string isKindOfClass:[NSNull class]]  || [[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]] length]==0){
//空
}else{
//不为空
}