Replace assertions in slice method with alert func

Paralayout/GeometryAdditions.swift

@@ -14,6 +14,7 @@
 // limitations under the License.
 //
 
+import os
 import UIKit
 
 // MARK: - Operator Overloads
@@ -144,6 +145,8 @@ extension CGRect {
 
  /// Divides the receiver in two.
  ///
+ /// The `slice` will always have a length of the specified `amount` in the perpendicular axis to the `edge`. The `remainder` will have the length remaining along that axis, clamped to zero if the `amount` is longer than the receiver's length.
+ ///
  /// - parameter from: The edge from which the amount is interpreted.
  /// - parameter amount: The size of the slice (absolute).
  /// - returns: A tuple (slice: A rect with a width/height of the `amount`, remainder: A rect with a width/height of
@@ -152,34 +155,42 @@ extension CGRect {
  switch edge {
  case .minXEdge:
  // Left.
- assert(amount <= width, "Cannot slice rect \(self) at edge \(edge) by \(amount)!")
+ if amount > width {
+ ParalayoutAlertForInvalidSliceDimensions()
+ }
  return (
  CGRect(x: minX, y: minY, width: amount, height: height),
- CGRect(x: minX + amount, y: minY, width: width - amount, height: height)
+ CGRect(x: minX + amount, y: minY, width: max(width - amount, 0), height: height)
  )
 
  case .minYEdge:
  // Top.
- assert(amount <= height, "Cannot slice rect \(self) at edge \(edge) by \(amount)!")
+ if amount > height {
+ ParalayoutAlertForInvalidSliceDimensions()
+ }
  return(
  CGRect(x: minX, y: minY, width: width, height: amount),
- CGRect(x: minX, y: minY + amount, width: width, height: height - amount)
+ CGRect(x: minX, y: minY + amount, width: width, height: max(height - amount, 0))
  )
 
  case .maxXEdge:
  // Right.
- assert(amount <= width, "Cannot slice rect \(self) at edge \(edge) by \(amount)!")
+ if amount > width {
+ ParalayoutAlertForInvalidSliceDimensions()
+ }
  return(
  CGRect(x: maxX - amount, y: minY, width: amount, height: height),
- CGRect(x: minX, y: minY, width: width - amount, height: height)
+ CGRect(x: minX, y: minY, width: max(width - amount, 0), height: height)
  )
 
  case .maxYEdge:
  // Bottom.
- assert(amount <= height, "Cannot slice rect \(self) at edge \(edge) by \(amount)!")
+ if amount > height {
+ ParalayoutAlertForInvalidSliceDimensions()
+ }
  return(
  CGRect(x: minX, y: maxY - amount, width: width, height: amount),
- CGRect(x: minX, y: minY, width: width, height: height - amount)
+ CGRect(x: minX, y: minY, width: width, height: max(height - amount, 0))
  )
  }
  }
@@ -282,3 +293,20 @@ extension NSDirectionalEdgeInsets {
  }
 
 }
+
+// MARK: -
+
+nonisolated
+private func ParalayoutAlertForInvalidSliceDimensions() {
+ os_log(
+ "%@",
+ log: ParalayoutLog,
+ type: .default,
+ """
+ Paralayout detected a slice with an `amount` larger than the receiver's length in the specified axis. \
+ Set a symbolic breakpoint for \"ParalayoutAlertForInvalidSliceDimensions\" to debug. \
+ Call stack:
+ \(Thread.callStackSymbols.dropFirst(1).joined(separator: "\n"))
+ """
+ )
+}

Paralayout/UIView+Alignment.swift

@@ -170,8 +170,6 @@ extension AlignmentContext {
 
 // MARK: -
 
-@MainActor
-private let ParalayoutLog = OSLog(subsystem: "com.squareup.Paralayout", category: "layout")
 
 /// Triggered when an alignment method is called that uses mismatched position types, i.e. aligning a view's leading or
 /// trailing edge to another view's left or right edge, or vice versa. This type of mismatch is likely to look correct

ParalayoutLog.swift

@@ -0,0 +1,20 @@
+//
+// Copyright © 2024 Block, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import os
+
+nonisolated
+internal let ParalayoutLog = OSLog(subsystem: "com.squareup.Paralayout", category: "layout")