IOS UI-标签（Label）的高级应用

 //
 //  BWLabel.h
 //  IOS_0119_label
 //
 //  Created by ma c on 16/1/19.
 //  Copyright © 2016年 博文科技. All rights reserved.
 //

 #import <UIKit/UIKit.h>

 typedef NS_ENUM(NSInteger, BWTextAlignment) {
     BWTextAlignmentTop      = ,
     BWTextAlignmentBottom   = ,
     BWTextAlignmentCenter   = ,
     BWTextAlignmentLeftTop  = ,//文字－左上
     BWTextAlignmentLeftDown = ,//文字－左下
     BWTextAlignmentRightTop = ,//文字－右上
     BWTextAlignmentRightDown= //文字－右下
 };

 @interface BWLabel : UILabel

 @property (nonatomic, assign) BWTextAlignment bowenTextAlignment;

 @end

 //
 //  BWLabel.m
 //  IOS_0119_label
 //
 //  Created by ma c on 16/1/19.
 //  Copyright © 2016年 博文科技. All rights reserved.
 //

 #import "BWLabel.h"

 @implementation BWLabel

 - (instancetype)initWithFrame:(CGRect)frame
 {
     self = [super initWithFrame:frame];
     if (self) {
         _bowenTextAlignment = BWTextAlignmentCenter;

     }
     return self;
 }

 - (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines
 {
     CGRect bowenRect = [super textRectForBounds:bounds limitedToNumberOfLines:numberOfLines];

     switch (_bowenTextAlignment) {
         case BWTextAlignmentTop:
             bowenRect.origin.x = (bounds.size.width - bowenRect.size.width)/;
             bowenRect.origin.y = bounds.origin.y;
             break;
         case BWTextAlignmentCenter:
             bowenRect.origin.x = (bounds.size.width - bowenRect.size.width)/;
             bowenRect.origin.y = bounds.origin.y + (bounds.size.height - bowenRect.size.height)/;
             break;
         case BWTextAlignmentBottom:
             bowenRect.origin.x = (bounds.size.width - bowenRect.size.width)/;
             bowenRect.origin.y = bounds.origin.y + bounds.size.height - bowenRect.size.height;
         case BWTextAlignmentLeftTop:
             bowenRect.origin.y = bounds.origin.y;
             bowenRect.origin.x = ;
             break;
         case BWTextAlignmentLeftDown:
             bowenRect.origin.y = bounds.origin.y + bounds.size.height - bowenRect.size.height;
             bowenRect.origin.x = ;
             break;
         case BWTextAlignmentRightTop:
             bowenRect.origin.y = bounds.origin.y;
             bowenRect.origin.x = bounds.size.width - bowenRect.size.width;
             break;
         case BWTextAlignmentRightDown:
             bowenRect.origin.y = bounds.origin.y + bounds.size.height - bowenRect.size.height;
             bowenRect.origin.x = bounds.size.width - bowenRect.size.width;
             break;
     }
     return bowenRect;
 }

 - (void)drawTextInRect:(CGRect)rect
 {
     CGRect bowenRect = [self textRectForBounds:rect limitedToNumberOfLines:self.lineBreakMode];

     [super drawTextInRect:bowenRect];
 }
 @end

 //
 //  ViewController.m
 //  IOS_0119_label
 //
 //  Created by ma c on 16/1/19.
 //  Copyright © 2016年 博文科技. All rights reserved.
 //

 #import "ViewController.h"
 #import "BWLabel.h"
 #import <CoreText/CoreText.h>

 @interface ViewController ()

 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];

     NSMutableAttributedString *bowenAttributedString = [[NSMutableAttributedString alloc] initWithString:@"举头望明月,低头思故乡"];

     //字体颜色NSForegroundColorAttributeName
     //字体大小NSFontAttributeName
     NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:
               [UIColor redColor], NSForegroundColorAttributeName,
     [UIFont systemFontOfSize:], NSFontAttributeName, nil];

     [bowenAttributedString setAttributes:dict range:NSMakeRange(, )];

     //kCTUnderlineStyleAttributeName设置下划线
     [bowenAttributedString addAttribute:(NSString *)kCTUnderlineStyleAttributeName value:(id)[NSNumber numberWithInt:kCTUnderlineStyleSingle] range:NSMakeRange(, )];
     NSLog(@"%@",bowenAttributedString);

     //进行替换属性字符串通过NSRange
     [bowenAttributedString replaceCharactersInRange:NSMakeRange(, ) withString:@"伤"];

     BWLabel *label = [[BWLabel alloc] initWithFrame:CGRectMake(, , , )];
     //label.text = @"123666";
     label.attributedText = bowenAttributedString;
     label.backgroundColor = [UIColor groupTableViewBackgroundColor];
     label.bowenTextAlignment = BWTextAlignmentTop;
     [self.view addSubview:label];
 }

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event

{

NSLog(@"%@",[touches valueForKey:@"view"]);

}

 @end

我们先从NSMutableAttributedString看起（47行）到（48行），与（54行）到（67行）

//（1）通过给出的range替换属性字符串

- (void)replaceCharactersInRange:(NSRange)range withString:(NSString *)str;

//（2）通过给出的NSDictionary（设置属性字符串）

- (void)setAttributes:(nullable NSDictionary<NSString *, id> *)attrs range:(NSRange)range;

我们看一下属性字符串可以设置的Keys

//

//  NSAttributedString.h

//  UIKit

//

//  Copyright (c) 2011-2015, Apple Inc. All rights reserved.

//

#import <Foundation/NSAttributedString.h>

#import <UIKit/UIKitDefines.h>

@class NSFileWrapper;

@class NSURL;

NS_ASSUME_NONNULL_BEGIN

//字体

UIKIT_EXTERN NSString * const NSFontAttributeName NS_AVAILABLE(10_0, 6_0);   
//段落样式
UIKIT_EXTERN NSString * const NSParagraphStyleAttributeName NS_AVAILABLE(10_0, 6_0);

//文字颜色
UIKIT_EXTERN NSString * const NSForegroundColorAttributeName NS_AVAILABLE(10_0, 6_0);

//文字颜色背景
UIKIT_EXTERN NSString * const NSBackgroundColorAttributeName NS_AVAILABLE(10_0, 6_0);

//设置连体属性，取之味NSNumber对象（整数），0表示没有连体字符串，1表示使用默认连体字符串
UIKIT_EXTERN NSString * const NSLigatureAttributeName NS_AVAILABLE(10_0, 6_0);           
//设置字符间距
UIKIT_EXTERN NSString * const NSKernAttributeName NS_AVAILABLE(10_0, 6_0);

//设置删除线
UIKIT_EXTERN NSString * const NSStrikethroughStyleAttributeName NS_AVAILABLE(10_0, 6_0);

//下划线
UIKIT_EXTERN NSString * const NSUnderlineStyleAttributeName NS_AVAILABLE(10_0, 6_0);

//填充部分颜色
UIKIT_EXTERN NSString * const NSStrokeColorAttributeName NS_AVAILABLE(10_0, 6_0);

//设置笔画宽度
UIKIT_EXTERN NSString * const NSStrokeWidthAttributeName NS_AVAILABLE(10_0, 6_0);

//阴影属性
UIKIT_EXTERN NSString * const NSShadowAttributeName NS_AVAILABLE(10_0, 6_0);

//文本特殊效果
UIKIT_EXTERN NSString *const NSTextEffectAttributeName NS_AVAILABLE(10_10, 7_0);

//文本附件，取值为NSTextAttachment对象，用于图文混排CoreText
UIKIT_EXTERN NSString * const NSAttachmentAttributeName NS_AVAILABLE(10_0, 7_0);

//设置链接属性，点击后调用浏览器打开指定URL地址
UIKIT_EXTERN NSString * const NSLinkAttributeName NS_AVAILABLE(10_0, 7_0);

//设置基线偏移值，正，上偏，负下偏
UIKIT_EXTERN NSString * const NSBaselineOffsetAttributeName NS_AVAILABLE(10_0, 7_0);

//设置下划线
UIKIT_EXTERN NSString * const NSUnderlineColorAttributeName NS_AVAILABLE(10_0, 7_0);

//设置删除线的颜色
UIKIT_EXTERN NSString * const NSStrikethroughColorAttributeName NS_AVAILABLE(10_0, 7_0);  
//设置字形倾斜度，取值为NSNumber（float），正，向右倾斜，负，向左倾斜

UIKIT_EXTERN NSString * const NSObliquenessAttributeName NS_AVAILABLE(10_0, 7_0);  
//设置文本横向拉伸属性，取之为NSnumber（float）正值，横向拉伸文本，负值，横向压缩文本

UIKIT_EXTERN NSString * const NSExpansionAttributeName NS_AVAILABLE(10_0, 7_0);           
//设置蚊子书写方向，从左向右书写或者从右向左书写

UIKIT_EXTERN NSString * const NSWritingDirectionAttributeName NS_AVAILABLE(10_6, 7_0);

//设置蚊子拍版方向，取值为NSNumber对象（整数），0横排文本，1竖排文本
UIKIT_EXTERN NSString * const NSVerticalGlyphFormAttributeName NS_AVAILABLE(10_7, 6_0);

苹果自己的API用来设置属性字符串的Keys的
 或者，刚才的操作～在初始化的时候setAttributes也是可以的

 

//－－－－－－－－－－－－－－－然后我们看看类蔟中的内容－－－－－－－－－－－－－－－
//（1）设置属性字符串的属性 

- (void)addAttribute:(NSString *)name value:(id)value range:(NSRange)range;

//（2）通过NSDictionary设置属性字符串的属性 

- (void)addAttributes:(NSDictionary<NSString *, id> *)attrs range:(NSRange)range; 

//（3）删除属性字符串的属性

- (void)removeAttribute:(NSString *)name range:(NSRange)range;

//（4）替换属性字符串

- (void)replaceCharactersInRange:(NSRange)range withAttributedString:(NSAttributedString*)attrString;

//（5）插入属性字符串

- (void)insertAttributedString:(NSAttributedString *)attrString atIndex:(NSUInteger)loc;

//（7）拼接属性字符串
- (void)appendAttributedString:(NSAttributedString *)attrString;

//（8）删除属性字符串

- (void)deleteCharactersInRange:(NSRange)range;

//（9）设置属性字符串

- (void)setAttributedString:(NSAttributedString *)attrString;

- (void)beginEditing;

- (void)endEditing;

有人会问了为什么我的属性字符串加载不出来，是因为，我加了如下的代码
这就涉及到了CoreText和CoreGray还有，OpenGLES了，先看代码，听我逐一讲解

#import <CoreText/CoreText.h>

- (void)drawRect:(CGRect)rect

{

[super drawRect:rect];

NSAttributedString *attriString = orangeAttributeString;

CGContextRef ctx = UIGraphicsGetCurrentContext();

CGContextConcatCTM(ctx, CGAffineTransformScale(CGAffineTransformMakeTranslation(0, rect.size.height), 1.f, -1.f));

CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attriString);

CGMutablePathRef path = CGPathCreateMutable();

CGPathAddRect(path, NULL, rect);

CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), path, NULL);

CFRelease(path);

CFRelease(framesetter);

CTFrameDraw(frame, ctx);

CFRelease(frame);

}

今天继续更新（关于CGContextRef）的介绍

相当于重写了UIView的drawRect方法（CoreGraphics）

UIKIT_EXTERN CGContextRef __nullable UIGraphicsGetCurrentContext(void) CF_RETURNS_NOT_RETAINED;
这是CGContextRef的定义

#define UIKIT_EXTERN         extern __attribute__((visibility ("default")))

这是UIKIT_EXTERN的定义
偏向C的语言方法
CGContextRef是CoreFoundation框架的对象
释放的时候ARC控制不了，所以内存管理使用CFRelease来释放CoreFoundation对象

转自：http://user.qzone.qq.com/282187892?ptlang=2052