collect() 创建集合
辅助函数 collect 为给定数组返回一个新的 Illuminate\Support\Collection 实例
```
$collection = collect([
[
'user_id' => '1',
'title' => 'Helpers in Laravel',
'content' => 'Create custom helpers in Laravel',
'category' => 'php'
],
[
'user_id' => '2',
'title' => 'Testing in Laravel',
'content' => 'Testing File Uploads in Laravel',
'category' => 'php'
]
]);
```
