我正在为 OS X 制作一个小型服务器应用程序，并且我正在使用 NSTextView 来记录有关已连接客户端的一些信息。
每当我需要记录某些内容时，我都会以这种方式将新消息附加到 NSTextView 的文本中：
- (void)logMessage:(NSString *)message
{
if (message) {
self.textView.string = [self.textView.string stringByAppendingFormat:@"%@\n",message];
}
}
在此之后，我希望 NSTextField（或者我应该说包含它的 NSClipView）向下滚动以显示其文本的最后一行（显然它应该仅在最后一行不可见时滚动，在事实上，如果新行是我记录的第一行，它已经在屏幕上，所以不需要向下滚动）。
我怎样才能以编程方式做到这一点？
【问题讨论】：
标签： macos cocoa nstextview
找到解决方案：
- (void)logMessage:(NSString *)message
{
if (message) {
[self appendMessage:message];
}
}
- (void)appendMessage:(NSString *)message
{
NSString *messageWithNewLine = [message stringByAppendingString:@"\n"];
// Smart Scrolling
BOOL scroll = (NSMaxY(self.textView.visibleRect) == NSMaxY(self.textView.bounds));
// Append string to textview
[self.textView.textStorage appendAttributedString:[[NSAttributedString alloc]initWithString:messageWithNewLine]];
if (scroll) // Scroll to end of the textview contents
[self.textView scrollRangeToVisible: NSMakeRange(self.textView.string.length, 0)];
}
【讨论】：
let scroll = abs(self.logTextView.visibleRect.maxY - self.logTextView.bounds.maxY) < kScrollThreshold（带有kScrollThreshold 设置为 25。）
从 OS 10.6 开始，它就像 nsTextView.scrollToEndOfDocument(self) 一样简单。
【讨论】：
斯威夫特 4 + 5
let smartScroll = self.textView.visibleRect.maxY == self.textView.bounds.maxY
self.textView.textStorage?.append("new text")
if smartScroll{
self.textView.scrollToEndOfDocument(self)
}
【讨论】：
我已经搞砸了一段时间，因为我无法让它可靠地工作。我终于让我的代码工作了，所以我想把它作为回复发布。
我的解决方案允许您手动滚动，同时将输出添加到视图中。一旦滚动到 NSTextView 的绝对底部，自动滚动将恢复（如果启用，即）。
第一个类别仅在需要时才#import 这个...
FSScrollToBottomExtensions.h：
@interface NSView (FSScrollToBottomExtensions)
- (float)distanceToBottom;
- (BOOL)isAtBottom;
- (void)scrollToBottom;
@end
FSScrollToBottomExtensions.m：
@implementation NSView (FSScrollToBottomExtensions)
- (float)distanceToBottom
{
NSRect visRect;
NSRect boundsRect;
visRect = [self visibleRect];
boundsRect = [self bounds];
return(NSMaxY(visRect) - NSMaxY(boundsRect));
}
// Apple's suggestion did not work for me.
- (BOOL)isAtBottom
{
return([self distanceToBottom] == 0.0);
}
// The scrollToBottom method provided by Apple seems unreliable, so I wrote this one
- (void)scrollToBottom
{
NSPoint pt;
id scrollView;
id clipView;
pt.x = 0;
pt.y = 100000000000.0;
scrollView = [self enclosingScrollView];
clipView = [scrollView contentView];
pt = [clipView constrainScrollPoint:pt];
[clipView scrollToPoint:pt];
[scrollView reflectScrolledClipView:clipView];
}
@end
...为自己创建一个“OutputView”，它是 NSTextView 的子类：
FSOutputView.h：
@interface FSOutputView : NSTextView
{
BOOL scrollToBottomPending;
}
FSOutputView.m：
@implementation FSOutputView
- (id)setup
{
...
return(self);
}
- (id)initWithCoder:(NSCoder *)aCoder
{
return([[super initWithCoder:aCoder] setup]);
}
- (id)initWithFrame:(NSRect)aFrame textContainer:(NSTextContainer *)aTextContainer
{
return([[super initWithFrame:aFrame textContainer:aTextContainer] setup]);
}
- (void)dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
[super dealloc];
}
- (void)awakeFromNib
{
NSNotificationCenter *notificationCenter;
NSView *view;
// viewBoundsDidChange catches scrolling that happens when the caret
// moves, and scrolling caused by pressing the scrollbar arrows.
view = [self superview];
[notificationCenter addObserver:self
selector:@selector(viewBoundsDidChangeNotification:)
name:NSViewBoundsDidChangeNotification object:view];
[view setPostsBoundsChangedNotifications:YES];
// viewFrameDidChange catches scrolling that happens because text
// is inserted or deleted.
// it also catches situations, where window resizing causes changes.
[notificationCenter addObserver:self
selector:@selector(viewFrameDidChangeNotification:)
name:NSViewFrameDidChangeNotification object:self];
[self setPostsFrameChangedNotifications:YES];
}
- (void)handleScrollToBottom
{
if(scrollToBottomPending)
{
scrollToBottomPending = NO;
[self scrollToBottom];
}
}
- (void)viewBoundsDidChangeNotification:(NSNotification *)aNotification
{
[self handleScrollToBottom];
}
- (void)viewFrameDidChangeNotification:(NSNotification *)aNotification
{
[self handleScrollToBottom];
}
- (void)outputAttributedString:(NSAttributedString *)aAttributedString
flags:(int)aFlags
{
NSRange range;
BOOL wasAtBottom;
if(aAttributedString)
{
wasAtBottom = [self isAtBottom];
range = [self selectedRange];
if(aFlags & FSAppendString)
{
range = NSMakeRange([[self textStorage] length], 0);
}
if([self shouldChangeTextInRange:range
replacementString:[aAttributedString string]])
{
[[self textStorage] beginEditing];
[[self textStorage] replaceCharactersInRange:range
withAttributedString:aAttributedString];
[[self textStorage] endEditing];
}
range.location += [aAttributedString length];
range.length = 0;
if(!(aFlags & FSAppendString))
{
[self setSelectedRange:range];
}
if(wasAtBottom || (aFlags & FSForceScroll))
{
scrollToBottomPending = YES;
}
}
}
@end
...你可以在这个类中添加一些更方便的方法（我已经把它剥离了），这样你就可以输出一个格式化的字符串。
- (void)outputString:(NSString *)aFormatString arguments:(va_list)aArguments attributeKey:(NSString *)aKey flags:(int)aFlags
{
NSMutableAttributedString *str;
str = [... generate attributed string from parameters ...];
[self outputAttributedString:str flags:aFlags];
}
- (void)outputLineWithFormat:(NSString *)aFormatString, ...
{
va_list args;
va_start(args, aFormatString);
[self outputString:aFormatString arguments:args attributeKey:NULL flags:FSAddNewLine];
va_end(args);
}
【讨论】：
我有一些自定义的 NSTextView 和自定义输入法，所以我的选择是使用：
self.scrollView.contentView.scroll(NSPoint(x: 1, y: self.textView.frame.size.height))
【讨论】：