RE：自转，滚动，项目符号，缩进的UIScrollView，与归属串(RE: autorotatin

2019-10-16 14:21发布

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这是产生了一个谎言，因为我有很大帮助在把它在一起，贡献者，似乎可以公平地后的结果（作为一个答案，下同）。 如果您正在寻找涉及iOS和核心文本和滚动归属串的例子，在这里，他们组装。

一些加分：

包装：

这是由属性串的lineBreakMode，默认为包装完成。 您将无法取回字符串中的软换行符（不像在可可，其中NSTextView放入字符串“\ n”字符）。 但你并不需要。 你可以依靠的核心文本的Framesetter为您提供字符串的高度在给定的框架 - 只要你已经把领先的信息进入属性串。

CATextLayer：

这是得心应手的工作。 所有你需要做的就是指定一个属性串，并将其包装和借鉴。 如果你有一个简短的字符串，以显示与选择的字体，这是伟大的。 但CATextLayer不承认领导或缺口，因此对于这个项目，我直接画上的CALayer。

字体：

我坚持CTFontRef在大多数情况下，由于需要建立在iOS的一个属性串，它给出了准确的领先，但有些时候，它更容易使用UIFont工作。 这里有一个方法来一个CTFontRef（转换fontr ）到UIFont： 

NSString *sFontName = (NSString *)CTFontCopyName(fontr, kCTFontPostScriptNameKey);
UIFont *font = [UIFont fontWithName:sFontName size:CTFontGetSize(fontr)];
CGSize sizeString = [string sizeWithFont:font];
[sFontName release];

如果从头开始创建一个UIFont，要知道，它会接受空格的字体名族的一部分，也可以粉碎他们在一起，但“大胆”必须用连字符隔开： 

self.fontTickerNormal = [UIFont fontWithName:@"Helvetica Neue" 
                                        size:18.0f]; // OK
self.fontTickerIndent = [UIFont fontWithName:@"HelveticaNeue" 
                                        size:16.0f]; // OK too 
self.fontTickerBold = [UIFont fontWithName:@"HelveticaNeue-Bold" 
                                      size:18.0f];   // both the smash and the hyphen are required

CTFontRef更简单。 所有名称部可以用空格隔开。 以下工作正常： 

 self.fontrTickerBold = CTFontCreateWithName((CFStringRef)@"Helvetica Neue Bold", 18.0f, NULL);

回答样本遵循...

Answer 1:

准备组件：大多数的例子是更容易阅读，因为它们组装串及其属性都在一个地方（即明显的例子 ），但是如果你不挂到所有的组件，你会得到不好的访问异常时，视图使用字符串，因此它似乎最好在UIViewController的viewDidLoad中设置了一切： 

- (void)viewDidLoad {
[super viewDidLoad];

// FONTS ETC.

// Prepare fonts for the ticker display.
self.fontrTickerNormal = CTFontCreateWithName((CFStringRef)@"Helvetica Neue", 18.0f, NULL);
self.fontrTickerBold = CTFontCreateWithName((CFStringRef)@"Helvetica Neue Bold", 18.0f, NULL);
self.fontrTickerIndent = CTFontCreateWithName((CFStringRef)@"Helvetica Neue", 16.0f, NULL);
// Determine width of bullet sub-indent
// (Use a UIFont and UIKit's sizeWithFont. No need to fuss with framesetter and leading here; all we need is width.)
UIFont *fontTickerIndent_uif = [UIFont fontWithName:@"Helvetica Neue" size:16.0f]; 
NSString *stringWithBullet = [NSString stringWithUTF8String:"\u2022"]; // bullet char
NSString *stringWithBulletPlusSpace = [stringWithBullet stringByAppendingString:@"  "];
CGSize sizeBulletPlusSpace = [stringWithBulletPlusSpace sizeWithFont:fontTickerIndent_uif];
self.fWidthBulletPlusSpace = sizeBulletPlusSpace.width;
// Prepare bulleted string to which text can be appended
NSString *stringBulletBuild = [@"\n" stringByAppendingString:stringWithBullet];
stringBulletBuild = [stringBulletBuild stringByAppendingString:@"\t"];
self.sBulletedLineBreak = stringBulletBuild;

// Initialize the collections that will hold onto the individual strings and dicts via alloc, as opposed to an autoreleased method, so that we can control the order in which they are released in viewDidUnload. (If dicts were to be released before the strings that use them, there would be a bad-access crash):
NSMutableArray *asmarrTickerStringsNew = [[NSMutableArray alloc] initWithCapacity:20]; // guess
self.asmarrTickerStrings = asmarrTickerStringsNew;
[asmarrTickerStringsNew release];
NSMutableArray *dmarrTickerAttributesNew = [[NSMutableArray alloc] initWithCapacity:20]; // one per string
self.dmarrTickerAttributes = dmarrTickerAttributesNew;
[dmarrTickerAttributesNew release];
// Don't initialize the cumulative-string ppty (mattrStgr) here. There is no way of appending to an empty CFMutableAttributedStringRef, so you have to wait till the first string goes through addProgressTickerLine.

// STYLE SETTINGS:

// paragStyleNormal:
CFIndex countSettings = 3; // normal and bold styles both have 3 settings
// - left alignment (the default, but just in case)
CTTextAlignment alignment = kCTLeftTextAlignment;
CTParagraphStyleSetting styleAlignLeft = { kCTParagraphStyleSpecifierAlignment, sizeof(CTTextAlignment), &alignment };
// - wrapping (again the default, but just in case)
CTLineBreakMode wrapping = kCTLineBreakByWordWrapping;
CTParagraphStyleSetting styleWrapped = { kCTParagraphStyleSpecifierLineBreakMode, sizeof(CTLineBreakMode), &wrapping };
// - normal leading (so framesetter calculates the correct height)
CGFloat fLeadingNormal = CTFontGetLeading(self.fontrTickerNormal);
CTParagraphStyleSetting styleLeadingNormal = { kCTParagraphStyleSpecifierLineSpacingAdjustment, sizeof(CGFloat), &fLeadingNormal };
CTParagraphStyleSetting arrSettingsNormal[] = { styleAlignLeft, styleWrapped, styleLeadingNormal };
self.paragStyleNormal = CTParagraphStyleCreate(arrSettingsNormal, countSettings);
// paragStyleBold:
// - bold leading (otherwise this style is same as normal)
CGFloat fLeadingBold = CTFontGetLeading(self.fontrTickerBold);
CTParagraphStyleSetting styleLeadingBold = { kCTParagraphStyleSpecifierLineSpacingAdjustment, sizeof(CGFloat), &fLeadingBold };
CTParagraphStyleSetting arrSettingsBold[] = { styleAlignLeft, styleWrapped, styleLeadingBold };
self.paragStyleBold = CTParagraphStyleCreate(arrSettingsBold, countSettings);
// paragStyleIndent:
// - indented leading (font is smaller)
CGFloat fLeadingIndent = CTFontGetLeading(self.fontrTickerIndent);
CTParagraphStyleSetting styleLeadingIndent = { kCTParagraphStyleSpecifierLineSpacingAdjustment, sizeof(CGFloat), &fLeadingIndent };
// - Indent the first line up to the bullet.
CGFloat indentFirstLineHead = 15.0f; 
CTParagraphStyleSetting styleFirstLineHeadIndent = { kCTParagraphStyleSpecifierFirstLineHeadIndent, sizeof(CGFloat), &indentFirstLineHead };
// - Add a tab stop to allow for the bullet and some following space.  
self.tabStop = CTTextTabCreate(alignment, (double)self.fWidthBulletPlusSpace, NULL); 
CTTextTabRef tabStopPtr[] = { self.tabStop };
self.cfarrTabStop = CFArrayCreate(NULL, (const void **) tabStopPtr, 1, NULL); 
CTParagraphStyleSetting styleTabStops = { kCTParagraphStyleSpecifierTabStops, sizeof(CTTextTabRef), &cfarrTabStop };
// - Indent the wrapped lines to the same point as the tab stop.
CGFloat indentHead = indentFirstLineHead + self.fWidthBulletPlusSpace;
CTParagraphStyleSetting styleHeadIndent = { kCTParagraphStyleSpecifierHeadIndent, sizeof(CGFloat), &indentHead };
// Put paragStyleIndent together.
countSettings += 3; // 3 style settings added (firstLineHeadIndent, tabStop, and HeadIndent)
CTParagraphStyleSetting arrSettingsIndent[] = { styleAlignLeft, styleWrapped, styleLeadingIndent, styleFirstLineHeadIndent, styleTabStops, styleHeadIndent };  
self.paragStyleIndent = CTParagraphStyleCreate(arrSettingsIndent, countSettings);

// LAYER AND SCROLLVIEW

// Set up the layer for the progress ticker.
CGSize sizeTicker = self.svProgressTicker.layer.bounds.size;
// Frame the layer:
/*
 - Don't add any padding to the X origin; the scrollview apparently figures some into its bounds automatically.
 - Do add some padding to the Y origin; otherwise the first string will hug the top.
 - Decrease the width to allow for the scrollbar, which the scrollview bounds do not account for.
 - Height is 0 for now, since it doesn't have any strings yet.
 */
CGRect rectTickerInset = CGRectMake(0.0f, kMargin, sizeTicker.width - kMargin, 0.0f);
CALayer *layerTicker = [CALayer layer];
[layerTicker setFrame:rectTickerInset];
// Assign this controller as the delegate and add it to the scrollview's root layer. 
// (See headnote to the drawLayer method.)
[layerTicker setDelegate:self];
self.layProgressTicker = layerTicker;
[svProgressTicker.layer addSublayer:self.layProgressTicker];
// Set the scrollView's contentSize per the layer's frame -- which will become taller with each appended string until it exceeds the scrollView's bounds.
[self.svProgressTicker setContentSize:CGSizeMake(rectTickerInset.size.width, rectTickerInset.size.height)];
[self.svProgressTicker setClipsToBounds:YES]; // otherwise the contents will overflow the border.

}

追加的字符串：

（这些常量:) 

#define kTickerStyleNormal           0
#define kTickerStyleIndent           1
#define kTickerStyleBold             2
#define kTickerStyleFirstLine        3

/**
 Appends the string arg to the Progress Ticker scrollView, styled per uiStyle.
 Note: String arg should NOT have any line breaks.
 */
- (void) addProgressTickerLine:(NSString *)string 
                       inStyle:(uint8_t)uiStyle {

// Determine the font.
CTFontRef fontr = nil;
switch (uiStyle) {
    case kTickerStyleNormal:
        fontr = self.fontrTickerNormal;
        break;
    case kTickerStyleIndent:
        fontr = self.fontrTickerIndent;
        break;
    case kTickerStyleBold:
        fontr = self.fontrTickerBold;
        break;
    case kTickerStyleFirstLine:
        fontr = self.fontrTickerBold;
        break;
    default:
        fontr = self.fontrTickerNormal;
        break;
}

// Prepare the paragraph style (preassembled in viewWillAppear), to govern inter-line height and indentation. 
// At the same time, add the initial line break.
CTParagraphStyleRef paragStyle = NULL; 
switch (uiStyle) {
    case kTickerStyleNormal:
        string = [@"\n" stringByAppendingString:string];
        paragStyle = self.paragStyleNormal;
        break;
    case kTickerStyleBold:
        // For main un-indented lines, simply add a line break.
        string = [@"\n" stringByAppendingString:string];
        paragStyle = self.paragStyleBold;
        break;
    case kTickerStyleFirstLine: {
        paragStyle = self.paragStyleBold;
        // No line break for the first line.
        // (Q: Why not avoid this case by putting line break at the end, rather than the beginning?)
        // (A: The indented string would then require 2 steps to sandwich it between the bullet-tab and the line break.)
        break;
    }
    case kTickerStyleIndent: {
        // For indented bullet lines, prepend lineBreak-bullet-tab to the string.
        string = [self.sBulletedLineBreak stringByAppendingString:string];
        // Assign the indented paragStyle.
        paragStyle = self.paragStyleIndent; 
        break;
    }
    default: // just in case
        paragStyle = self.paragStyleNormal;
        break;
}

// Determine the text (foreground) color per...
UIColor *colorHSV = [UIColor blueColor]; // switch-case omitted

// PUT IT ALL TOGETHER.

// Combine the above into a dictionary of attributes.
CFStringRef keys[] = { kCTFontAttributeName, kCTParagraphStyleAttributeName, kCTForegroundColorAttributeName };
CFTypeRef values[] = { fontr, paragStyleIndent, colorHSV.CGColor };
CFDictionaryRef dictr = CFDictionaryCreate(NULL, 
                                           (const void **)&keys, 
                                           (const void **)&values,
                                           sizeof(keys) / sizeof(keys[0]), 
                                           &kCFTypeDictionaryKeyCallBacks, 
                                           &kCFTypeDictionaryValueCallBacks);
[self.dmarrTickerAttributes addObject:(id)dictr]; // provides for release

// Use the attributes dictionary to make an attributed string out of the plain string.
CFAttributedStringRef attrStgr = CFAttributedStringCreate(kCFAllocatorDefault, (CFStringRef)string, dictr);    
[self.asmarrTickerStrings addObject:(id)attrStgr]; // provides for release
// Adding an object to a collection increments its retain count, so attrStgr are now at count 2 and should be decremented to 1; they will be brought to 0 upon release of the collections.
CFRelease(attrStgr);
CFRelease(dictr);

// If cumulative attrStg is nil, initialize it with a maxLength of 0 to indicate that it is unlimited.
if (!self.mattrStgr)
    self.mattrStgr = CFAttributedStringCreateMutableCopy(kCFAllocatorDefault, 0, attrStgr); 
// Else append the newly completed attrStg, using the method suggested in the CFMutableAttributedString class ref overview.
else {
    CFRange rangeAppend = CFRangeMake(CFAttributedStringGetLength(self.mattrStgr), 0);
    CFAttributedStringReplaceAttributedString(self.mattrStgr, rangeAppend, attrStgr);
}

// DISPLAY IT. 

// Now that the new string has been appended, call the method that will adjust the contentSize, trigger the draw method, and scroll to the end.
[self adjustProgressTickerFrame];

// Do NOT release attrstg or any of its styling components here. They are needed cumulative string property is voided. They have been propertized so that they can be released in dealloc (here in viewDidUnload).

}

调整高度，来电drawLayer，并滚动到底： 

/**
 Adjust the height of the scrollView and its content layer to accommodate newly appended strings and/or orientation change, redraw the layer, and scroll to the bottom.
 Called at the end of addProgressTickerLine and upon willAnimateRotationToInterfaceOrientation.
 */
- (void) adjustProgressTickerFrame {

// Get the width within which the text has to fit in the view's current frame.
CGSize sizeTickerView = self.svProgressTicker.layer.bounds.size;
CGFloat fWidthInset = sizeTickerView.width - kMargin;

// Make a framesetter in order to get the size of the cumulative string.
/*
 Note re Leading: 
 - The framesetter will suggest too short a height unless the attributed string has paragraphStyle attributes that specify the leading.
 - But if you attempt to do an efficient setNeedsDisplay:InRect routine, drawing only the last-appended string per its individual height, framesetter will report the the hard line breaks as a full line, not just as leading, so you'll end up with dimensions that are much too tall. There's no choice but to get the full size and draw the full cumulative string each time.
 */
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(self.mattrStgr);
CFIndex length = CFAttributedStringGetLength(self.mattrStgr);
CFRange textRange = CFRangeMake(0, length);
CFRange fitRange;
CGSize sizeString = CTFramesetterSuggestFrameSizeWithConstraints(framesetter, textRange, NULL, CGSizeMake(fWidthInset, CGFLOAT_MAX), &fitRange);

// Round the reported height up. Dimensions are reported as very precise fractions, but framing and drawing is by whole pixels.
CGFloat fHeight = ceilf(sizeString.height);

// Reframe the layer.
CGRect rectTickerInset = CGRectMake(0.0f, kMargin, sizeTickerView.width - kMargin, fHeight); 
[self.layProgressTicker setFrame:rectTickerInset];

// Adjust the scrollView's contentSize.
// (It should be slightly taller than the layer, to add padding at top and bottom.)
[self.svProgressTicker setContentSize:CGSizeMake(fWidthInset, (fHeight + (kMargin*2)))];

// Redraw the entire layer.
[self.layProgressTicker setNeedsDisplay];

// If the layer is now taller than the scrollView's bounds, scroll down.
// Do NOT use animation. 
// (If you do when the view first appears, it won't scroll down far enough, should the view be assigned lots of string content initially. (Presumably the initial autorotation anim prevents this one from being completed.) And afterwards, it doesn't make any difference; there's a spring action that happens regardless.)
CGFloat fHeightExcess = fHeight - (sizeTickerView.height - (kMargin*2)); 
if (fHeightExcess > 1.0f)
    [self.svProgressTicker setContentOffset:CGPointMake(0.0f, fHeightExcess) animated:NO];

}

画： 

/**
 CALayer's delegate method for drawing its content, triggered by calling setNeedsDisplay on the layer. 

 This controller is assigned as the layer's delegate, and calls setNeedsDisplay when:
 1) a string is appended
 2) the device is rotated into a different aspect ratio

 Q: Why not subclass UIScrollView and have IT be the delegate? After all, the class ref says the view associated with the layer must be the delegate.
 A1: Apparently "associated" in Apple-speak means as in view to its ROOT layer. Sublayers can have any delegate you choose.
 A2: If scrollView is the delegate and does the content drawing, the app will crash. ScrollView probably issues setNeedsDisplay:inRect: gazillions of times as it scrolls, overwhelming the processor.
 */
- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx {

// Get the rect of the entire area available for drawing.
// (We cannot use the layer's frame rect directly because it has origin insets; they would be doubled if used here too.)
CGRect drawingRect = CGRectMake(0.0f, 0.0f, self.layProgressTicker.frame.size.width, self.layProgressTicker.frame.size.height); 

// Turn the context upside down to match the layer's orientation.
// (The context origin is at the lower left, whereas the layer origin is at the upper left.)
CGContextSetTextMatrix(ctx, CGAffineTransformIdentity);
CGContextTranslateCTM( ctx, drawingRect.origin.x, drawingRect.size.height );
CGContextScaleCTM( ctx, 1, -1 );

// Make a rectangular path in which to draw.
CGMutablePathRef path = CGPathCreateMutable(); 
CGPathAddRect(path, NULL, drawingRect);

// Use Core Text's framesetter to frame the cumulative (mutable) attributed string inside the rectangular path.
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(self.mattrStgr);
CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), path, NULL);    
CFRelease(framesetter); // ok to release here; it's not part of "frame"
CFRelease(path);

// Draw the framesetter frame.
CTFrameDraw(frame, ctx);
CFRelease(frame);

}

自动旋转： 

/*
 Autorotation methods are called in this order:
    1) shouldAutorotate
    2) willRotate
    3) willAnimate
    4) didRotate
 */
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation {  
// Return YES to support all 4 orientations.
return YES;
}

- (void) willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {
// "When this method is called, the interfaceOrientation property still contains the view’s original orientation." (So hang onto it.)
// You can't wait until willAnimate because, by then, that property will have been set to the new orientation.
// Which leaves a mystery: The didRotateFromInterfaceOrientation is called AFTER willAnimate, and at that point the view controller still is able to send in the fromInterfaceOrientation arg.
self.bFromPortrait = UIInterfaceOrientationIsPortrait([self interfaceOrientation]);    
}

- (void) willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {

// If rotating from portrait to landscape or vice versa, the text layers need adjustment. 
BOOL bToPortrait = UIInterfaceOrientationIsPortrait(toInterfaceOrientation);

if (self.bFromPortrait != bToPortrait) 
    [self adjustProgressTickerFrame];

}

我想我有这个权利：这里是如何卸载所有这些东西（保留属性也发布的dealloc）： 

- (void)viewDidUnload {

// It's unlikely that this view will go away and then come back, so viewDidLoad assumes all properties are null -- therefore nullify/release EVERYTHING here.

self.svProgressTicker = nil;
self.layProgressTicker = nil;
self.vSyncInstructions = nil;
self.tlSyncInstructions = nil;
self.btnSyncEtc = nil;

// Release the cumulative attributed string BEFORE releasing any of its component strings.
CFRelease(self.mattrStgr);
// Nullifying the retained collections will release them -- and their contents, whose retainCounts were incremented upon addition to the collection. So it's important to nullify the strings collection first, then the attr dicts.
self.asmarrTickerStrings = nil;
self.dmarrTickerAttributes = nil;
// Now we can release the "created" settings, then their components.
CFRelease(self.paragStyleNormal);
CFRelease(self.paragStyleBold);
CFRelease(self.paragStyleIndent);
CFRelease(self.tabStop);
CFRelease(self.cfarrTabStop);
CFRelease(self.fontrTickerNormal);
CFRelease(self.fontrTickerBold);
CFRelease(self.fontrTickerIndent);
CFRelease(self.fontrInstructions);
self.fontInstructionsBenchmark = nil;

[super viewDidUnload];

}



Answer 2:

这里是斯威夫特很好的解决方案

let label = UILabel()
label.frame = CGRect(x: 40, y: 100, width: 280, height: 600)
label.textColor = UIColor.lightGray
label.numberOfLines = 0

let arrayString = [
    "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",
    "Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.",
    "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.",
    "Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
]

label.attributedText = add(stringList: arrayString, font: label.font, bullet: "")

self.view.addSubview(label)

添加项目符号属性

func add(stringList: [String],
         font: UIFont,
         bullet: String = "\u{2022}",
         indentation: CGFloat = 20,
         lineSpacing: CGFloat = 2,
         paragraphSpacing: CGFloat = 12,
         textColor: UIColor = .gray,
         bulletColor: UIColor = .blue) -> NSAttributedString {

    let textAttributes: [NSAttributedStringKey: Any] = [NSAttributedStringKey.font: font, NSAttributedStringKey.foregroundColor: textColor]
    let bulletAttributes: [NSAttributedStringKey: Any] = [NSAttributedStringKey.font: font, NSAttributedStringKey.foregroundColor: bulletColor]

    let paragraphStyle = NSMutableParagraphStyle()
    let nonOptions = [NSTextTab.OptionKey: Any]()
    paragraphStyle.tabStops = [
        NSTextTab(textAlignment: .left, location: indentation, options: nonOptions)]
    paragraphStyle.defaultTabInterval = indentation
    //paragraphStyle.firstLineHeadIndent = 0
    //paragraphStyle.headIndent = 20
    //paragraphStyle.tailIndent = 1
    paragraphStyle.lineSpacing = lineSpacing
    paragraphStyle.paragraphSpacing = paragraphSpacing
    paragraphStyle.headIndent = indentation

    let bulletList = NSMutableAttributedString()
    for string in stringList {
        let formattedString = "\(bullet)\t\(string)\n"
        let attributedString = NSMutableAttributedString(string: formattedString)

        attributedString.addAttributes(
            [NSAttributedStringKey.paragraphStyle : paragraphStyle],
            range: NSMakeRange(0, attributedString.length))

        attributedString.addAttributes(
            textAttributes,
            range: NSMakeRange(0, attributedString.length))

        let string:NSString = NSString(string: formattedString)
        let rangeForBullet:NSRange = string.range(of: bullet)
        attributedString.addAttributes(bulletAttributes, range: rangeForBullet)
        bulletList.append(attributedString)
    }

    return bulletList
}

下面是结果：



文章来源: RE: autorotating, scrolling, bulleted, indented UIScrollView with attributed strings
标签： objective-c ios uiscrollview calayer core-text
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