UILabel

// 设置label每一行文字的最大宽度
    // 为了保证计算出来的数值 跟 真正显示出来的效果 一致
    self.contentLabel.preferredMaxLayoutWidth = [UIScreen mainScreen].bounds.size.width - 20;

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下面通过例子，给UILabel的文字后面跟上一个表情：

//创建NSTextAttachment
    NSTextAttachment *attachment = [[NSTextAttachment alloc] init];
    attachment.image = [UIImage imageNamed:@"emoji"];

    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:@"后面跟着图片"];
    [attributedString addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(0, 6)];
    [attributedString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:16] range:NSMakeRange(0, 6)];
    NSAttributedString *attachmentString = [NSAttributedString attributedStringWithAttachment:attachment];
    [attributedString insertAttributedString:attachmentString atIndex:6];

    //设置attributedText
    _label.attributedText = attributedString;

效果如下：

上图的例子中，emoji图片偏大，位置也偏上，如何调整？参考Center NSTextAttachment image next to single line UILabel。

可以通过调整bounds来解决：

    NSTextAttachment *attachment = [[NSTextAttachment alloc] init];
    attachment.image = [UIImage imageNamed:@"emoji"];
    attachment.bounds = CGRectMake(0, -5, 20, 20);

调整之后的效果如下：

也可以继承NSTextAttachment，然后重写- (CGRect)attachmentBoundsForTextContainer:(NSTextContainer *)textContainer proposedLineFragment:(CGRect)lineFrag glyphPosition:(CGPoint)position characterIndex:(NSUInteger)charIndex方法：

@interface MYNSAttachment : NSTextAttachment
@end

@implementation MYNSAttachment

- (CGRect)attachmentBoundsForTextContainer:(NSTextContainer *)textContainer proposedLineFragment:(CGRect)lineFrag glyphPosition:(CGPoint)position characterIndex:(NSUInteger)charIndex
{
    return CGRectMake( 0 , -5 , lineFrag.size.height , lineFrag.size.height);
}

@end

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UIFont

UIFont代表字体，常见创建方法有以下几个：
+ (UIFont *)systemFontOfSize:(CGFloat)fontSize;   系统默认字体
+ (UIFont *)boldSystemFontOfSize:(CGFloat)fontSize;  粗体
+ (UIFont *)italicSystemFontOfSize:(CGFloat)fontSize;  斜体