iOS-UILabel充分利用NSAttributedStrin

1、同一块文本中设置不同字体、颜色，及换行

代码如下：

- (void)viewDidLoad {
    [super viewDidLoad];
    NSString *text = @"百家姓：\n赵钱孙李，周吴郑王。\n冯陈褚卫，蒋沈韩杨。\n朱秦尤许，何吕施张。\n孔曹严华，金魏陶姜。\n戚谢邹喻，柏水窦章。\n云苏潘葛，奚范彭郎。\n鲁韦昌马，苗凤花方。\n俞任袁柳，酆鲍史唐。\n费廉岑薛，雷贺倪汤。\n滕殷罗毕，郝邬安常。";
    CGFloat labelHeight = [self heightOfLabelWithText:text font:[UIFont systemFontOfSize:12.0] width:self.view.frame.size.width-20];
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10, 50, self.view.frame.size.width-20, labelHeight)];
    label.font = [UIFont systemFontOfSize:12.0];
    label.textColor = [UIColor darkGrayColor];
    label.attributedText = [self configLabelTextWithText:text label:label boundaryLength:4];
    [self.view addSubview:label];
}

#pragma mark - 计算高度
- (CGFloat)heightOfLabelWithText:(NSString *)text font:(UIFont *)font width:(CGFloat)width{
    UILabel *testLabel = [[UILabel alloc] init];
    testLabel.font = font;
    CGRect oldFrame = testLabel.frame;
    oldFrame.size.width = width;
    [testLabel setFrame:oldFrame];
    testLabel.attributedText = [self configLabelTextWithText:text label:testLabel boundaryLength:4];
    [testLabel sizeToFit];
    return testLabel.frame.size.height;
}

#pragma mark - 设置具体文本属性
- (NSAttributedString *)configLabelTextWithText:(NSString *)labelText label:(UILabel *)label boundaryLength:(NSInteger)boundaryLenght{
    NSString  *text = labelText; //[NSString stringWithFormat:@"%@",[labelText stringByReplacingOccurrencesOfString:@"\\n" withString:@"\r\n" ]];
    label.numberOfLines = 0;
    NSMutableAttributedString * attributedText = [[NSMutableAttributedString alloc] initWithString:text];
    [attributedText setAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:14.0], NSForegroundColorAttributeName:[[UIColor orangeColor] colorWithAlphaComponent:0.5]} range:NSMakeRange(0, boundaryLenght)];
    
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    [paragraphStyle setLineSpacing:(8.0-(label.font.lineHeight - label.font.pointSize))];
    [paragraphStyle setLineBreakMode:label.lineBreakMode];
    [paragraphStyle setAlignment:label.textAlignment];
    [attributedText addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, text.length)];
    return attributedText;
}

代码实现效果：

image.png

2、文本中添加图片

只修改configLabelTextWithText方法，代码如下：

- (NSAttributedString *)configLabelTextWithText:(NSString *)labelText label:(UILabel *)label boundaryLength:(NSInteger)boundaryLenght{
    NSString  *text = labelText; // [NSString stringWithFormat:@"%@",[labelText stringByReplacingOccurrencesOfString:@"\\n" withString:@"\r\n" ]];
    label.numberOfLines = 0;
    NSMutableAttributedString * attributedText = [[NSMutableAttributedString alloc] initWithString:text];
    [attributedText setAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:14.0],NSForegroundColorAttributeName:[[UIColor orangeColor] colorWithAlphaComponent:0.5]} range:NSMakeRange(0, boundaryLenght)];
    
    //创建NSTextAttachment
    NSTextAttachment *attachment = [[NSTextAttachment alloc] init];
    attachment.image = [UIImage imageNamed:@"NaturePatterns02.jpg"];
    attachment.bounds = CGRectMake(0, (label.font.capHeight-10)/2.0, 16, 10);
    
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    [paragraphStyle setLineSpacing:(8.0-(label.font.lineHeight - label.font.pointSize))];
    [paragraphStyle setLineBreakMode:label.lineBreakMode];
    [paragraphStyle setAlignment:label.textAlignment];
    [attributedText addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [text length])];
    NSAttributedString *attachmentString = [NSAttributedString attributedStringWithAttachment:attachment];
    [attributedText insertAttributedString:attachmentString atIndex:boundaryLenght+4];
    [attributedText insertAttributedString:attachmentString atIndex:text.length-20];
    return attributedText;
}

代码运行效果：

image.png

3、部分代码解释：

• 1> NSTextAttachment-bounds属性
  label添加图片中，attachment.bounds属性，宽高不用多说，至于纵坐标y值，如果设置为0，图片不一定会和文字对齐，会有一定的偏移，那么如何设置y值呢？
  请点击这里查看答案
  你会看到有个人这么说：
  

  image.png
  没错就是采用：(label.font.capHeight-image.size.height)/2.0

• 2> NSMutableParagraphStyle-lineSpacing属性
  lineSpacing属性要想符合UI的要求请参考我之前的文章->iOS-文字行高

• 3> 具体细节参考
  原博主文章-UILabel&UITextView文本嵌入图片处理