Assertion failure in UITextView _firstBaselineOffsetFromTop

问题

I was learning about the view debugger in Xcode and capturing the view hierarchy with Debug > View Debugging > Capture View Hierarchy. However when I tried it in my app I got the following error:

Assertion failure in -[UITextView _firstBaselineOffsetFromTop], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3512.60.7/UITextView.m:1683

I could reproduce this in the following simple project:

import UIKit
class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let myTextView = UITextView()
        myTextView.frame = CGRect(x: 50, y: 50, width: 200, height: 100)
        myTextView.text = "This is a test."
        view.addSubview(myTextView)

    }
}

I saw here that it could be caused by not using auto layout. Is this really a bug that we have to wait for a fix? Is there a Swift workaround?

Update

The suggested duplicate looks like the same issue I am having. However, unlike that question, I am asking for a Swift workaround. The "answer" to that question was just a link (the same link that I already had above). I am voting to close the other way.

回答1:

Note do this in DEBUG builds only

A workaround to resolve this issue. Keep below category in your project. It worked for me.

@interface UITextView(MYTextView)

@end

@implementation UITextView (MYTextView)
- (void)_firstBaselineOffsetFromTop {

}

- (void)_baselineOffsetFromBottom {

}

@end

For swift

extension UITextView {
    func _firstBaselineOffsetFromTop() {
    }
    func _baselineOffsetFromBottom() {
    }
}

来源：https://stackoverflow.com/questions/37068231/assertion-failure-in-uitextview-firstbaselineoffsetfromtop