CODEWITHSUNDEEP
objective-cuitableviewswift
KVISH
KVISH

Reputation: 13178

swift init not visible in objective-C

I'm trying to create init functions in Swift and create instances from Objective-C. The problem is that I don't see it in Project-Swift.h file and I'm not able to find the function while initializing. I have a function defined as below:

public init(userId: Int!) {
    self.init(style: UITableViewStyle.Plain)
    self.userId = userId
}

I even tried putting @objc(initWithUserId:) and I keep getting the same error again. Is there anything else I'm missing? How do I get the constructor visible to Objective-C code?

I read the below for this:

https://developer.apple.com/library/ios/documentation/swift/conceptual/swift_programming_language/Initialization.html

https://developer.apple.com/library/ios/documentation/swift/conceptual/buildingcocoaapps/interactingwithobjective-capis.html

How to write Init method in Swift

How to define optional methods in Swift protocol?

Upvotes: 34

Views: 20075

Answers (2)

Stefan
Stefan

Reputation: 300

use this one:

var index: NSInteger!

@objc convenience init(index: NSInteger) {
    self.init()

    self.index = index
}

Upvotes: 11

Nate Cook
Nate Cook

Reputation: 93276

The issue you're seeing is that Swift can't bridge optional value types -- Int is a value type, so Int! can't be bridged. Optional reference types (i.e., any class) bridge correctly, since they can always be nil in Objective-C. Your two options are to make the parameter non-optional, in which case it would be bridged to ObjC as an int or NSInteger:

// Swift
public init(userId: Int) {
    self.init(style: UITableViewStyle.Plain)
    self.userId = userId
}

// ObjC
MyClass *instance = [[MyClass alloc] initWithUserId: 10];

Or use an optional NSNumber?, since that can be bridged as an optional value:

// Swift
public init(userId: NSNumber?) {
    self.init(style: UITableViewStyle.Plain)
    self.userId = userId?.integerValue
}

// ObjC
MyClass *instance = [[MyClass alloc] initWithUserId: @10];    // note the @-literal

Note, however, you're not actually treating the parameter like an optional - unless self.userId is also an optional you're setting yourself up for potential runtime crashes this way.

Upvotes: 41

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