LCEssentials/Documentation/UIKit.md

# LCEssentials — UIKit

UIKit-era helpers: programmatic layout & constraints, view/control extensions,
navigation, table/collection helpers, and drop-in components (image picker, image
zoom, snackbar, GIF loading).

Foundation/value-type helpers are in [Extensions.md](Extensions.md); SwiftUI
helpers in [SwiftUI.md](SwiftUI.md).

Every section is a collapsible block — click a heading to expand it.

## Contents

- [Layout & Constraints](#layout--constraints)
- [Views & Controls](#views--controls)
- [Navigation & Controllers](#navigation--controllers)
- [Collections & Tables](#collections--tables)
- [Media & Components](#media--components)

---

## Layout & Constraints

<details>
<summary><b>UIView</b> — programmatic constraints, chainable anchors</summary>

### `enum AnchorType`
The anchor to pin when using `setConstraintsTo`. Cases: `all`, `top`, `bottom`,
`leading`, `trailing`, `left`, `right`, `centerX`, `centerY`, `width`, `heigth`
*(sic)*, `topToBottom`, `bottomToTop`, `leadingToTrailing`, `trailingToLeading`,
plus `…GreaterThanOrEqualTo` / `…LessThanOrEqualTo` variants.

### `@discardableResult func setConstraintsTo(parentView: UIView, anchorType: AnchorType, value: CGFloat, safeArea: Bool = false) -> Self`
Activate one constraint against `parentView`. Remembers `parentView` (in
`viewReference`) so follow-up calls can omit it. `safeArea: true` pins top/bottom
to the safe-area guide (iOS 11+).

```swift
card.addSubview(label)
label.setConstraintsTo(parentView: card, anchorType: .top, value: 12, safeArea: false)
     .setConstraints(.leading, 16)
     .setConstraints(.trailing, -16)
```

### `@discardableResult func setConstraintsTo(_ parentView:_ anchorType:_ value:_ safeArea: Bool = false) -> Self`
Positional-argument shorthand for the above.

### `@discardableResult func setConstraintsTo(anchorType: AnchorType, value: CGFloat, safeArea: Bool = false) -> UIView`
Reuse the last `parentView` (`viewReference`). **Traps** with `fatalError` if no
`parentView` was set first.

### `@discardableResult func setConstraints(_ anchorType: AnchorType, _ value: CGFloat, _ safeArea: Bool = false) -> UIView`
Positional shorthand for the reuse form — the one you chain.

### `func setConstraints(_ toScrollView: UIScrollView, direction: UICollectionView.ScrollDirection = .vertical)`
Pin `self` as the single content view of a scroll view (edges + matching
width/height, with a low-priority constraint on the scroll axis). Traps if
`self` is itself a `UIScrollView`.

```swift
scrollView.addSubview(content)
content.setConstraints(scrollView, direction: .vertical)
```

### Constraint accessors
`widthConstraint`, `heightConstraint`, `leadingConstraint`, `trailingConstraint`,
`topConstraint`, `bottomConstraint`, `centerXConstraints`, `centerYConstraints` —
the first matching `NSLayoutConstraint` found by walking up the hierarchy.

```swift
box.widthConstraint?.constant = 120
UIView.animate(withDuration: 0.2) { self.view.layoutIfNeeded() }
```

### `func findConstraint(attribute: NSLayoutConstraint.Attribute, for view: UIView) -> NSLayoutConstraint?`
Search self and ancestors for a constraint on `attribute` involving `view`.

### `func constraints(on anchor:) -> [NSLayoutConstraint]`
Constraints touching a given `NSLayoutYAxisAnchor` / `XAxisAnchor` / `Dimension` of `self`.

### `@discardableResult func setHeight(size:) -> Self` / `setHeight(min:)` / `setWidth(size:)` / `setWidth(min:)`
Activate a fixed or minimum dimension constraint.

```swift
avatar.setWidth(size: 44).setHeight(size: 44)
```

### `func setWidth(_ toView: UIView? = nil, constant: CGFloat, _ multiplier: CGFloat = 0) -> Self` / `setHeight(...)`
Dimension relative to another view (`multiplier`) or fixed (`multiplier == 0`).

### Frame setters
`setX(x:)`, `setY(y:)`, `setFrameWidth(width:)`, `setFrameHeight(height:)` — mutate
`self.frame` directly (manual layout, not Auto Layout).

</details>

<details>
<summary><b>UIView</b> — hierarchy, appearance, effects</summary>

### `static var className: String`
`String(describing: self)`.

```swift
UIButton.className   // "UIButton"
```

### `func addSubview(_ subview:, translatesAutoresizingMaskIntoConstraints: Bool = false)` / `addSubviews(_ subviews: [UIView], …)`
Add a view (or many) and set `translatesAutoresizingMaskIntoConstraints` in one call.

```swift
view.addSubviews([header, body, footer])   // all ready for Auto Layout
```

### `func subviews<T>(ofType _: T.Type) -> [T]`
All descendants of a type, recursively.

```swift
formView.subviews(ofType: UITextField.self)
```

### `func findAView<T>(_ ofType: T.Type) -> T?`
First descendant of a type.

### `var parentViewController: UIViewController?`
Nearest owning view controller (walks the responder chain).

### `var borderColor: UIColor?` / `var borderWidth: CGFloat` / `var cornerRadius: CGFloat`
Layer border/corner shortcuts (`cornerRadius` also sets `masksToBounds`).

```swift
card.cornerRadius = 12
card.borderWidth = 1
card.borderColor = .separator
```

### `func setRadius(top: Bool, bottom: Bool, radius: CGFloat = 8)`
Round only the top and/or bottom corners.

```swift
sheet.setRadius(top: true, bottom: false, radius: 16)
```

### `func applyShadow(color:offSet:radius:opacity:shouldRasterize: Bool = true, rasterizationScaleTo: = UIScreen.main.scale)` / `func removeShadow()`
Layer shadow with rasterisation on by default.

```swift
card.applyShadow(color: .black, offSet: CGSize(width: 0, height: 2),
                 radius: 6, opacity: 0.15)
```

### `func insertBlurView(style: UIBlurEffect.Style, color: UIColor = .black, alpha: CGFloat = 0.9)`
Insert a full-bleed `UIVisualEffectView` behind the content.

### `func drawCircle(inCoord x:y:with radius:strokeColor: = .red, fillColor: = .gray, isEmpty: Bool = false) -> [String: Any]`
Add a circular `CAShapeLayer`; returns `["path": UIBezierPath, "layer": CAShapeLayer]`.

### `var isRightToLeft: Bool`
Effective RTL layout direction.

### `var screenshot: UIImage?` / `func asImage() -> UIImage`
Render the view to an image (`screenshot` via the legacy context, `asImage` via `UIGraphicsImageRenderer`).

```swift
let png = chartView.asImage().pngData()
```

### `var globalPoint: CGPoint?` / `var globalFrame: CGRect?` / `var absolutePosition: CGRect`
Origin/frame converted to window coordinates.

### `func fadeIn(withDuration: TimeInterval = 1, withDelay: TimeInterval = 0, completionHandler: @escaping (Bool) -> Void)` / `func fadeOut(...)`
Animate `alpha` to 1 / 0. *(Completion-handler API — pre-dates async/await.)*

```swift
overlay.fadeOut { _ in overlay.removeFromSuperview() }
```

### `var viewReference: UIView?`
Scratch reference used internally by the chained `setConstraintsTo` calls.

</details>

<details>
<summary><b>GradientOrientation / EnumBorderSide</b></summary>

### `enum GradientOrientation`
`topRightBottomLeft`, `topLeftBottomRight`, `horizontal`, `vertical` — maps to a
`CAGradientLayer` start/end point pair. Passed to gradient helpers elsewhere in
the package.

### `enum EnumBorderSide`
`top`, `bottom`, `left`, `right` — which edge to draw a single-side border on.

</details>

<details>
<summary><b>UIStackView</b> — convenience init, bulk arranged-subview ops (iOS 9+)</summary>

### `convenience init(arrangedSubviews: [UIView]? = nil, axis: = .vertical, spacing: = 0, alignment: = .fill, distribution: = .fill, layoutMargins: = .zero, isMarginsRelative: Bool = true)`
One-call configured stack view.

```swift
let stack = UIStackView(arrangedSubviews: [title, subtitle],
                        axis: .vertical, spacing: 4)
```

### `func addArrangedSubviews(_ views: [UIView], translateAutoresizing: Bool = false)`
Add many arranged subviews, setting their autoresizing flag.

### `func removeAllArrangedSubviews(deactivateConstraints: Bool = true)`
Remove and dispose every arranged subview.

### `func removeSubview(view: UIView, deactivateConstraints: Bool = true)`
Remove one arranged subview (optionally deactivating its constraints and removing from the hierarchy).

### `func addSpace(_ size: CGFloat, backgroundColor: UIColor = .clear)`
Insert a fixed-size spacer view sized along the stack's axis.

```swift
stack.addArrangedSubviews([row1, row2])
stack.addSpace(24)
stack.addArrangedSubview(row3)
```

</details>

> `NSLayoutConstraint` helpers (`constraintWithMultiplier`, `matches(view:anchor:)`)
> and `[NSLayoutConstraint].filtered(view:anchor:)` are `internal` — used by the
> `UIView.constraints(on:)` accessors above, not called directly.

## Views & Controls

<details>
<summary><b>UIButton</b> — per-state accessors, all-state setters</summary>

### Per-state properties
`imageForNormal` / `imageForHighlighted` / `imageForSelected` / `imageForDisabled`,
`titleForNormal` / `…Highlighted` / `…Selected` / `…Disabled`,
`titleColorForNormal` / `…Highlighted` / `…Selected` / `…Disabled` — get/set
shortcuts for the matching `UIControl.State` (also `@IBInspectable`).

```swift
button.titleForNormal = "Save"
button.titleColorForDisabled = .tertiaryLabel
```

### `func setTitleForAllStates(_:)` / `func setTitleColorForAllStates(_:)` / `func setImageForAllStates(_:)`
Apply one value to `.normal`, `.selected`, `.highlighted`, `.disabled` at once.

```swift
button.setTitleColorForAllStates(.white)
```

### `func centerTextAndImage(spacing: CGFloat)`
Balance title/image edge insets so text + icon sit centred with `spacing` between them.

```swift
button.centerTextAndImage(spacing: 8)
```

</details>

<details>
<summary><b>UILabel</b></summary>

### `func lineNumbers() -> Int`
Rendered line count at the current width.

```swift
if bodyLabel.lineNumbers() > 3 { showMoreButton() }
```

### `var getEstimatedHeight: CGFloat`
Height the label would need to show its full text/attributed text unclipped.

</details>

<details>
<summary><b>UITextField</b></summary>

### `var placeholderColor: UIColor`
Get/set the placeholder text colour (rebuilds `attributedPlaceholder`; setter is a
no-op if no placeholder text is set).

```swift
field.placeholder = "Email"
field.placeholderColor = .secondaryLabel
```

### `func addPaddingLeft(_ padding: CGFloat)`
Inset the text from the left with an empty spacer view.

### `func addPaddingLeftIcon(_ image: UIImage, padding: CGFloat)`
Left view = an icon plus trailing padding.

```swift
field.addPaddingLeftIcon(UIImage(systemName: "magnifyingglass")!, padding: 8)
```

</details>

<details>
<summary><b>UIImageView</b> (<code>@MainActor</code>)</summary>

### `func changeColorOfImage(_ color: UIColor, image: UIImage?) -> UIImageView`
Set a template-rendered image tinted to `color`; returns `self`.

```swift
iconView.changeColorOfImage(.systemBlue, image: UIImage(named: "star"))
```

### `var encodeToBase64: String?`
JPEG (quality 0.6) of the current image as a Base64 string.

### `func addAspectRatioConstraint()` / `func removeAspectRatioConstraint()`
Add / remove a width-to-height constraint matching the current image's ratio.

```swift
photoView.image = photo
photoView.addAspectRatioConstraint()
```

</details>

<details>
<summary><b>UIImage</b> — recolour, resize, thumbnails, masks, init</summary>

### `func imageWithColor(color: UIColor) -> UIImage` / `func tintImage(color: UIColor) -> UIImage`
Return a copy filled / tinted with `color` (keeps the alpha shape).

```swift
let redIcon = icon.tintImage(color: .systemRed)
```

### `func backgroundColorTransparent(initialColor: UIColor, finalColor: UIColor) -> UIImage?`
Make pixels in a colour range transparent.

### `class func outlinedEllipse(size: CGSize, color: UIColor, lineWidth: CGFloat = 1) -> UIImage?`
Generate a stroked-ellipse image.

```swift
UIImage.outlinedEllipse(size: CGSize(width: 24, height: 24), color: .label)
```

### `func resizeImage(newWidth: CGFloat) -> UIImage`
Scale to `newWidth`, keeping the aspect ratio.

### `func createThumbnail(_ maxPixelSize: UInt) -> UIImage`
Fast down-sampled thumbnail via `CGImageSource`.

```swift
let thumb = fullImage.createThumbnail(200)
```

### `func maskWithAlphaImage(maskImage: UIImage) -> UIImage`
Use another image's alpha as a mask.

### `func isAnimated() -> Bool`
Whether the image has more than one frame.

### `init?(base64String: String, scale: CGFloat = 1)`
Decode a Base64 string to an image.

### `init(view: UIView)` — *`@MainActor`*
Rasterise a view into an image.

```swift
let snapshot = UIImage(view: cardView)
```

</details>

<details>
<summary><b>UIColor</b> — hex, components</summary>

### `convenience init(hex: String)`
Parse `#RGB`, `#RGBA`, `#RRGGBB`, or `#RRGGBBAA` (with or without `#`).

```swift
view.backgroundColor = UIColor(hex: "#1E88E5")
UIColor(hex: "FF0000CC")   // red at 80% alpha
```

### `var hexString: String?`
`#RRGGBB` (or `#RRGGBBAA` when alpha < 1).

### `var redValue` / `var greenValue` / `var blueValue` / `var alphaValue`
Individual channel values (`CGFloat`, via `CIColor`).

```swift
UIColor.systemBlue.redValue   // 0.0…1.0
```

</details>

<details>
<summary><b>UIScrollView</b> — snapshot, visible rect, paged scrolling</summary>

### `var snapshot: UIImage?`
Image of the **entire** content size (not just the visible part) — works on
`UITableView` / `UICollectionView` too.

### `var visibleRect: CGRect`
The currently visible content region.

### `var offsetInPage: CGFloat`
Fractional position within the current page height (`0.0`…`1.0`).

### `func scrollUp(animated:)` / `scrollDown(animated:)` / `scrollLeft(animated:)` / `scrollRight(animated:)`
Move one page (respects `isPagingEnabled`). `animated` defaults to `true`.

```swift
nextButton.onTap = { scrollView.scrollRight() }
```

### `enum orientation`
`horizontal` / `vertical` — helper enum used by scroll utilities.

</details>

<details>
<summary><b>UITapGestureRecognizer</b></summary>

### `func didTapAttributedTextInLabel(label: UILabel, textToTouch: String) -> Bool`
Whether the tap landed on a given substring of a label's attributed text — for
making part of a label tappable.

```swift
@objc func handleTap(_ g: UITapGestureRecognizer) {
    if g.didTapAttributedTextInLabel(label: termsLabel, textToTouch: "Terms of Use") {
        openTerms()
    }
}
```

</details>

## Navigation & Controllers

<!-- batch 11 -->

## Collections & Tables

<!-- batch 12 -->

## Media & Components

<!-- batch 13 -->