很多人在谈论iPhone/iPad上的富文本，也有很多人知道NSAttributedString。
但是如何使用NSAttributedString呢？我搜索了很久，没有找到任何线索。
我知道如何设置一个NSAttributedString，那么如何在iPhone/iPad上显示带富文本的文本呢？
官方文档说它应该与CoreText.Framework一起使用，这是什么意思？
是否有像这样简单的方法呢？
NSAttributedString *str;
.....
UILabel *label;
label.attributedString = str;
从 iOS 6.0 开始，你可以这样做：
NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:@"Hello. That is a test attributed string."];
[str addAttribute:NSBackgroundColorAttributeName value:[UIColor yellowColor] range:NSMakeRange(3,5)];
[str addAttribute:NSForegroundColorAttributeName value:[UIColor greenColor] range:NSMakeRange(10,7)];
[str addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"HelveticaNeue-Bold" size:20.0] range:NSMakeRange(20, 10)];
label.attributedText = str;
你应该看一下AliSoftware的OHAttributedLabel。它是UILabel的子类，可以绘制NSAttributedString，并提供方便的方法从UIKit类中设置NSAttributedString的属性。
从存储库中提供的示例：
#import "NSAttributedString+Attributes.h"
#import "OHAttributedLabel.h"
/**(1)** Build the NSAttributedString *******/
NSMutableAttributedString* attrStr = [NSMutableAttributedString attributedStringWithString:@"Hello World!"];
// for those calls we don't specify a range so it affects the whole string
[attrStr setFont:[UIFont systemFontOfSize:12]];
[attrStr setTextColor:[UIColor grayColor]];
// now we only change the color of "Hello"
[attrStr setTextColor:[UIColor redColor] range:NSMakeRange(0,5)];
/**(2)** Affect the NSAttributedString to the OHAttributedLabel *******/
myAttributedLabel.attributedText = attrStr;
// Use the "Justified" alignment
myAttributedLabel.textAlignment = UITextAlignmentJustify;
// "Hello World!" will be displayed in the label, justified, "Hello" in red and " World!" in gray.
注意：在iOS 6及以上版本，您可以使用UILabel的attributedText属性呈现带属性的字符串。
iOS 6中UILabel的文本对齐方式解决方案：使用NSMutableAttributedString并添加NSMutableParagraphStyle属性。类似于以下代码：
NSString *str = @"Hello World!";
NSRange strRange = NSMakeRange(0, str.length);
NSMutableAttributedString *attributedStr = [[NSMutableAttributedString alloc] initWithString:str];
NSMutableParagraphStyle *paragrahStyle = [[NSMutableParagraphStyle alloc] init];
[paragrahStyle setAlignment:NSTextAlignmentCenter];
[attributedStr addAttribute:NSParagraphStyleAttributeName value:paragrahStyle range:strRange];
myUILabel.attributedText = attributedStr;
@interface ExampleHTMLStringToAttributedString : NSObject<NSXMLParserDelegate>
+(NSAttributedString*) getAttributedStringForHTMLText:(NSString*)htmlText WithFontSize:(CGFloat)fontSize;
@end
@interface ExampleHTMLStringToAttributedString()
@property NSString *mpString;
@property NSMutableAttributedString *mpAttributedString;
@property CGFloat mfFontSize;
@property NSMutableString *appendThisString;
@property BOOL mbIsBold;
@property BOOL mbIsItalic;
@end
@implementation ExampleHTMLStringToAttributedString
@synthesize mpString;
@synthesize mfFontSize;
@synthesize mpAttributedString;
@synthesize appendThisString;
@synthesize mbIsBold;
@synthesize mbIsItalic;
//初始化方法，传入需要转换的字符串
- (id)initWithString:(NSString*)inString {
self = [super init];
if (self) {
if ([inString hasPrefix:@""]) {
mpString = inString;
} else {
mpString = [NSString stringWithFormat:@"%@", inString];
}
mpAttributedString = [NSMutableAttributedString new];
}
return self;
}
//将HTML格式的文本转换为NSAttributedString对象，fontSize为字体大小
+(NSAttributedString*) getAttributedStringForHTMLText:(NSString*)htmlText WithFontSize:(CGFloat)fontSize {
ExampleHTMLStringToAttributedString *me = [[ExampleHTMLStringToAttributedString alloc] initWithString:htmlText];
return [me getAttributedStringWithFontSize:fontSize];
}
//开始解析HTML文本
-(NSAttributedString*) getAttributedStringWithFontSize:(CGFloat)fontSize {
mfFontSize = fontSize;
// 解析XML
NSXMLParser *parser = [[NSXMLParser alloc] initWithData:[mpString dataUsingEncoding:NSUTF8StringEncoding]];
parser.delegate = self;
if (![parser parse]) {
return nil;
}
return mpAttributedString;
}
//拼接已经解析好的文本
-(void) appendTheAccumulatedText {
UIFont *theFont = nil;
if (mbIsBold && mbIsItalic) {
// https://dev59.com/TXM_5IYBdhLWcg3waiiJ
theFont = [UIFont fontWithName:@"Helvetica-BoldOblique" size:mfFontSize];
} else if (mbIsBold) {
theFont = [UIFont boldSystemFontOfSize:mfFontSize];
} else if (mbIsItalic) {
theFont = [UIFont italicSystemFontOfSize:mfFontSize];
} else {
theFont = [UIFont systemFontOfSize:mfFontSize];
}
NSAttributedString *appendThisAttributedString =
[[NSAttributedString alloc]
initWithString:appendThisString
attributes:@{NSFontAttributeName : theFont}];
[mpAttributedString appendAttributedString:appendThisAttributedString];
[appendThisString setString:@""];
}
#pragma NSXMLParserDelegate delegate
//开始解析XML文档
-(void)parserDidStartDocument:(NSXMLParser *)parser{
appendThisString = [NSMutableString new];
mbIsBold = NO;
mbIsItalic = NO;
}
//解析到开始标签
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
if ([elementName isEqualToString:@"body"]){
} else if ([elementName isEqualToString:@"i"]) {
[self appendTheAccumulatedText];
mbIsItalic = YES;
} else if ([elementName isEqualToString:@"b"]) {
[self appendTheAccumulatedText];
mbIsBold = YES;
}
}
//解析到结束标签
-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{
if ([elementName isEqualToString:@"body"]){
[self appendTheAccumulatedText];
} else if ([elementName isEqualToString:@"i"]) {
[self appendTheAccumulatedText];
mbIsItalic = NO;
} else if ([elementName isEqualToString:@"b"]) {
[self appendTheAccumulatedText];
mbIsBold = NO;
}
}
//解析到文本内容
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
[appendThisString appendString:string];
}
//解析出错
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError {
}
@end
使用方法如下：
self.myTextView.attributedText = [ExampleHTMLStringToAttributedString getAttributedStringForHTMLText:@"这是<b>加粗</b>文本" WithFontSize:self.myTextView.pointSize];
从iOS 6.0开始，您可以这样做：另一个示例代码。
NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:@"This is my test code to test this label style is working or not on the text to show other user"];
[str addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(0,31)];
[str addAttribute:NSBackgroundColorAttributeName value:[UIColor greenColor] range:NSMakeRange(61,10)];
[str addAttribute:NSFontAttributeName value: [UIFont fontWithName:@"Helvetica-Bold" size:13.0] range:NSMakeRange(32, 28)];
[str addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"Helvetica-Bold" size:13.0] range:NSMakeRange(65, 20)];
_textLabel.attributedText = str;
如果您使用Swift，请使用以下代码：
这将使标题文本变为粗体：Tilt
var title = NSMutableAttributedString(string: "Title Text")
title.addAttributes([NSFontAttributeName: UIFont(name: "AvenirNext-Bold", size: iCurrentFontSize)!], range: NSMakeRange(0, 4))
label.attributedText = title
我知道有点晚了，但这对其他人可能会有用。
NSMutableAttributedString* attrStr = [[NSMutableAttributedString alloc] initWithString:@"string" attributes:@{NSForegroundColorAttributeName:[UIColor blackColor]}];
[self.label setAttributedText:newString];