optional-binding | 易学教程

Naming convention for optional binding

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问题 One thing that originally discouraged me from incorporating too much optional binding in my code was the addition of more variable names. For example, I'd generally write: if bananasInBarrel != nil{ print("We have \(bananasInBarrel!) bananas in the barrel.") } Because the alternative seemed to get a bit messy: if let safeBananas = bananasInBarrel{ print("We have \(safeBananas) bananas in the barrel.") } That's a lot of bananas. I've seen people use something like b as the new variable name

Why use optional binding?

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问题 I am aware that this question is here, but it only partially answers my question and I cannot comment on the answer so I'm forced to post here. What is the difference between optional binding and just simply using ?. My understanding is when you use ? to unwrap a variable, if it contains a nil value then the code in which it is used isn't run. (Please correct me if this is not the case.) 回答1: You use optional binding ( if let ) if you have a block of code that you only want to run if the

Naming convention for optional binding

阅读更多关于 Naming convention for optional binding

One thing that originally discouraged me from incorporating too much optional binding in my code was the addition of more variable names. For example, I'd generally write: if bananasInBarrel != nil{ print("We have \(bananasInBarrel!) bananas in the barrel.") } Because the alternative seemed to get a bit messy: if let safeBananas = bananasInBarrel{ print("We have \(safeBananas) bananas in the barrel.") } That's a lot of bananas. I've seen people use something like b as the new variable name (which could get hard-to-read in a larger block of code), but I'm wondering if there's a generally

Conditional Binding: if let error – Initializer for conditional binding must have Optional type

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I am trying to delete a row from my Data Source and the following line of code: if let tv = tableView { causes the following error: Initializer for conditional binding must have Optional type, not UITableView Here is the full code: // Override to support editing the table view. func tableView(tableView: UITableView, commitEditingStyle editingStyle:UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) { if editingStyle == .Delete { // Delete the row from the data source if let tv = tableView { myData.removeAtIndex(indexPath.row) tv.deleteRowsAtIndexPaths([indexPath],

Conditional Binding: if let error – Initializer for conditional binding must have Optional type

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问题 I am trying to delete a row from my Data Source and the following line of code: if let tv = tableView { causes the following error: Initializer for conditional binding must have Optional type, not UITableView Here is the full code: // Override to support editing the table view. func tableView(tableView: UITableView, commitEditingStyle editingStyle:UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) { if editingStyle == .Delete { // Delete the row from the data source if let