C# NSString.Replace方法代码示例

		bool ShouldChangeCharacters (UITextField textField, NSRange range, string replacementString)
		{
			bool hasInvalidChars = replacementString.ToCharArray ().Any (c => !IsValidMorseCharacter (c));
		
			if (hasInvalidChars)
			{
				UIView.Animate (0.2f, 0f, UIViewAnimationOptions.Autoreverse,
					() => this.txtMorse.BackgroundColor = UIColor.Red,
					() => this.txtMorse.BackgroundColor = UIColor.White);

				return false;
			}

			// Morse only has uppercase characters.
			replacementString = replacementString.ToUpperInvariant ();
			var nativeString = new NSString (this.txtMorse.Text);
			this.txtMorse.Text = nativeString.Replace (range, new NSString (replacementString));

			// Remember last message.
			CrossSettings.Current.AddOrUpdateValue (SETTING_LAST_MESSAGE, this.txtMorse.Text);

			// Return FALSE because we update the content ourselves (uppercasing everything).
			return false;
		}

		protected virtual void PrepareEntry(UITableView tableview){
			SizeF size = _computeEntryPosition(tableview);
			
			_entry = new CustomTextField (new RectangleF (size.Width+10, (ContentView.Bounds.Height-size.Height)/2-10, 320-size.Width-20, size.Height+20));
			_delegate = new CustomTextFieldDelegate ();
			_entry.Delegate = _delegate;

			_entry.VerticalAlignment = UIControlContentVerticalAlignment.Center;

			TextLabel.BackgroundColor = UIColor.Clear;
			_entry.AutoresizingMask = UIViewAutoresizing.FlexibleWidth |
				UIViewAutoresizing.FlexibleLeftMargin;

			_entry.MaxCharacters = 5;

			_entry.Started += delegate {
				var position = tableview.IndexPathForCell(this);
				tableview.SelectRow(position, false, UITableViewScrollPosition.None);
			};

			_entry.ValueChanged += delegate {
				if (_element != null) {
					_element.Value = _entry.Text;
				}
			};
			_entry.EnablesReturnKeyAutomatically = true;
			_entry.Ended += (object sender, EventArgs e) => {
				if (_element != null) {
					_element.Value = _entry.Text;
					
					if (_element.OnValueChanged!=null)
						_element.OnValueChanged(_element);
				}
				
				var position = tableview.IndexPathForCell(this);
				if (tableview.IndexPathForSelectedRow!=null && position!=null && position.Compare(tableview.IndexPathForSelectedRow)==0){
					tableview.DeselectRow(position, false);
				}

			};
			_entry.ShouldChangeCharacters = (textField, range, replacement) => 
			{
				if (_element.MaxLength<0) return true;
				if (_element.MaxLength==0) return false;
				using (NSString original = new NSString(textField.Text))
				{
					var replace = original.Replace(range, new NSString(replacement));
					if (replace.Length>_element.MaxLength)
						return false;
				}
				return true;
			};

			_entry.AddTarget((object o, EventArgs r)=>{
				if (_element != null)
					_element.Value = _entry.Text;
				}, UIControlEvent.EditingChanged);
				
			_entry.ShouldReturn += delegate {
				Element elementToFocusOn = null;
				
				foreach (var c in ((Section)_element.Parent).Elements){
					if (c == _element)
						elementToFocusOn = c;
					else if (elementToFocusOn != null && c is EntryElement)
						elementToFocusOn = c as EntryElement;
				}
				if (elementToFocusOn != _element && elementToFocusOn!=null) {
					var cell = tableview.CellAt(elementToFocusOn.GetIndexPath());
					cell.BecomeFirstResponder();
				}
				else 
					_entry.ResignFirstResponder();

                if (_entry.ReturnKeyType == UIReturnKeyType.Go) {
                    _element.FireGo(this, EventArgs.Empty);
                }

				return true;
			};
			_entry.Started += delegate {
				EntryElement self = null;
				var returnType = _element.ReturnKeyType;

                if (returnType != UIReturnKeyType.Default) {
                    foreach (var e in (_element.Parent as Section).Elements){
                        if (e == _element)
                            self = _element;
                        else if (self != null && e is EntryElement)
                            returnType = UIReturnKeyType.Next;
                    }
                }
                _entry.ReturnKeyType = returnType;
			};
				
			ContentView.AddSubview (_entry);
		}