Open Radar

 
Summary:
I'm building a unit test that loops through an array of CGPoints. Inside the loop it tries to access the point's .x and .y fields. This crashes the app after a few iterations through the loop with an EXC_BAD_ACCESS error.

Steps to Reproduce:
1. Create a new iOS project in Xcode (template doesn't matter).
2. Add the following unit test case:

import XCTest
import CoreGraphics

class TestThatCrashesTests: XCTestCase {
    
  func testLerp() {

    let expected = [
      CGPoint(x: -100, y: -150),
      CGPoint(x: -80, y: -130),
      CGPoint(x: -60, y: -110),
      CGPoint(x: -40, y: -90),
      CGPoint(x: -20, y: -70),
      CGPoint(x: 0, y: -50),
      CGPoint(x: 20, y: -30),
      CGPoint(x: 40, y: -10),
      CGPoint(x: 60, y: 10),
      CGPoint(x: 80, y: 30),
      CGPoint(x: 100, y: 50)
      ]

    var i = 0
    for var t = 0.0; t <= 1.0; t += 0.1, ++i {

      // silly test, but it crashes here:
      XCTAssertEqual(0.0, expected[i].x)
      XCTAssertEqual(0.0, expected[i].y)
    }
  }
}

3. Run the tests, see the app crash.

Expected Results:
The current test should fail, but not crash the app.

Actual Results:
The test crashes after several iterations of the loop. It is not an array out of bounds, i.e. i is not > 10 when the app crashes but more like 3 or 4.