FieldRow.titlePercentage instead of FieldRow.textFieldPercentage (xma…

…rtlabs#965). Properly calculate FieldRow constraints.

* Deprecate FieldRowConformance.textFieldPercentage in favor of FieldRowConformance.titleLabelPercentage in order to fix alignment issues when using an accessory view/type on a FieldCell

* Include optional imageView in title width calculations. Only works for right-to-left languages in iOS 9.0 and higher since only app extension API is allowed. This prohibits determining of interface layout direction in older iOS versions.

* Rename titleLabelPercentage to titlePercentage as it should not only encompass the titleLabel’s width but also an optional imageView’s width. Also maintain a private calculatedTitlePercentage property instead of caching and resetting the row’s value after each constraint update.

If `titleFieldPercentage` is not set, the layout is not adjusted to make
up for potential accessory and/or image views. Instead a fixed constant
is used for the respective constraint. By moving this fixed constant to
the advanced layout calculation we not only solve the aforementioned
issue but also eliminate duplication of the the constant during
constraint setup.

Note that this could have also been achieved by simply declaring
`titleFieldPercentage` a non-optional variable and assigning a default
value of 0.3. Since this would represent both a code breaking as well as
somewhat of a semantic change the solution at hand was deemed preferable

Source/Rows/Common/FieldRow.swift

@@ -28,10 +28,10 @@ public protocol InputTypeInitiable {
     init?(string stringValue: String)
 }
 
-public protocol FieldRowConformance: FormatterConformance {
-    var textFieldPercentage: CGFloat? { get set }
-    var placeholder: String? { get set }
-    var placeholderColor: UIColor? { get set }
+public protocol FieldRowConformance : FormatterConformance {
+    var titlePercentage : CGFloat? { get set }
+    var placeholder : String? { get set }
+    var placeholderColor : UIColor? { get set }
 }
 
 extension Int: InputTypeInitiable {
@@ -86,8 +86,19 @@ open class FieldRow<Cell: CellType>: FormatteableRow<Cell>, FieldRowConformance,
     open var keyboardReturnType: KeyboardReturnTypeConfiguration?
 
     /// The percentage of the cell that should be occupied by the textField
-    open var textFieldPercentage: CGFloat?
-
+	@available (*, deprecated, message: "Use titleLabelPercentage instead")
+	open var textFieldPercentage : CGFloat? {
+		get {
+			return titlePercentage.map { 1 - $0 }
+		}
+		set {
+			titlePercentage = newValue.map { 1 - $0 }
+		}
+	}
+
+	/// The percentage of the cell that should be occupied by the title (i.e. the titleLabel and optional imageView combined)
+	open var titlePercentage: CGFloat?
+
     /// The placeholder for the textField
     open var placeholder: String?
 
@@ -126,7 +137,9 @@ open class _FieldCell<T> : Cell<T>, UITextFieldDelegate, TextFieldCell where T:
     private var awakeFromNibCalled = false
 
     open var dynamicConstraints = [NSLayoutConstraint]()
-
+
+	private var calculatedTitlePercentage: CGFloat = 0.7
+
     public required init(style: UITableViewCellStyle, reuseIdentifier: String?) {
 
         let textField = UITextField()
@@ -269,28 +282,31 @@ open class _FieldCell<T> : Cell<T>, UITextFieldDelegate, TextFieldCell where T:
             if let titleLabel = titleLabel, let text = titleLabel.text, !text.isEmpty {
                 views["label"] = titleLabel
                 dynamicConstraints += NSLayoutConstraint.constraints(withVisualFormat: "H:[imageView]-(15)-[label]-[textField]-|", options: NSLayoutFormatOptions(), metrics: nil, views: views)
-                dynamicConstraints.append(NSLayoutConstraint(item: textField,
-                                                             attribute: .width,
-                                                             relatedBy: (row as? FieldRowConformance)?.textFieldPercentage != nil ? .equal : .greaterThanOrEqual,
-                                                             toItem: contentView,
-                                                             attribute: .width,
-                                                             multiplier: (row as? FieldRowConformance)?.textFieldPercentage ?? 0.3,
-                                                             constant: 0.0))
-            } else {
+				dynamicConstraints.append(NSLayoutConstraint(item: titleLabel,
+				                                             attribute: .width,
+				                                             relatedBy: (row as? FieldRowConformance)?.titlePercentage != nil ? .equal : .lessThanOrEqual,
+				                                             toItem: contentView,
+				                                             attribute: .width,
+				                                             multiplier: calculatedTitlePercentage,
+				                                             constant: 0.0))
+            }
+            else{
                 dynamicConstraints += NSLayoutConstraint.constraints(withVisualFormat: "H:[imageView]-(15)-[textField]-|", options: [], metrics: nil, views: views)
             }
-        } else {
-            if let titleLabel = titleLabel, let text = titleLabel.text, !text.isEmpty {
+        }
+        else{
+			if let titleLabel = titleLabel, let text = titleLabel.text, !text.isEmpty {
                 views["label"] = titleLabel
                 dynamicConstraints += NSLayoutConstraint.constraints(withVisualFormat: "H:|-[label]-[textField]-|", options: [], metrics: nil, views: views)
-                dynamicConstraints.append(NSLayoutConstraint(item: textField,
-                                                             attribute: .width,
-                                                             relatedBy: (row as? FieldRowConformance)?.textFieldPercentage != nil ? .equal : .greaterThanOrEqual,
-                                                             toItem: contentView,
-                                                             attribute: .width,
-                                                             multiplier: (row as? FieldRowConformance)?.textFieldPercentage ?? 0.3,
-                                                             constant: 0.0))
-            } else {
+				dynamicConstraints.append(NSLayoutConstraint(item: titleLabel,
+				                                             attribute: .width,
+				                                             relatedBy: (row as? FieldRowConformance)?.titlePercentage != nil ? .equal : .lessThanOrEqual,
+				                                             toItem: contentView,
+				                                             attribute: .width,
+				                                             multiplier: calculatedTitlePercentage,
+				                                             constant: 0.0))
+            }
+            else{
                 dynamicConstraints += NSLayoutConstraint.constraints(withVisualFormat: "H:|-[textField]-|", options: .alignAllLeft, metrics: nil, views: views)
             }
         }
@@ -382,6 +398,27 @@ open class _FieldCell<T> : Cell<T>, UITextFieldDelegate, TextFieldCell where T:
 
     open func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
         return formViewController()?.textInputShouldEndEditing(textField, cell: self) ?? true
-    }
-
+	}
+
+	open override func layoutSubviews() {
+		super.layoutSubviews()
+		guard let row = (row as? FieldRowConformance) else { return }
+		guard let titlePercentage = row.titlePercentage else  { return }
+		var targetTitleWidth = bounds.size.width * titlePercentage
+		if let imageView = imageView, let _ = imageView.image, let titleLabel = titleLabel {
+			var extraWidthToSubtract = titleLabel.frame.minX - imageView.frame.minX // Left-to-right interface layout
+			if #available(iOS 9.0, *) {
+				if UIView.userInterfaceLayoutDirection(for: self.semanticContentAttribute) == .rightToLeft {
+					extraWidthToSubtract = imageView.frame.maxX - titleLabel.frame.maxX
+				}
+			}
+			targetTitleWidth -= extraWidthToSubtract
+		}
+		let targetTitlePercentage = targetTitleWidth / contentView.bounds.size.width
+		if calculatedTitlePercentage != targetTitlePercentage {
+			calculatedTitlePercentage = targetTitlePercentage
+			setNeedsUpdateConstraints()
+			updateConstraintsIfNeeded()
+		}
+	}
 }