如上述要求，我们可以给UILabel 添加一个类别方法，
@interface UILabel (ReadMore)
-(void)setReadMoreLabelContentMode;
@end
#import "UILabel+ReadMore.h"
#import <CoreText/CoreText.h>
@implementation UILabel (ReadMore)
-(void)setReadMoreLabelContentMode
{
NSArray *contents = [self getLinesArrayOfLabelRows];
if (contents.count <= 1) {
self.userInteractionEnabled = NO; // 如果一行就不显示查看更多，同时取消手势响应
return;
}
self.userInteractionEnabled=YES;
NSUInteger cutLength = 7; // 截取的长度20
NSMutableString *contentText = [[NSMutableString alloc] init];
for (NSInteger i = 0; i < self.numberOfLines; i++) {
if (i == self.numberOfLines - 1) { // 最后一行 进行处理加上.....
NSString *lastLineText = [NSString stringWithFormat:@"%@",contents[i]];
NSUInteger lineLength = lastLineText.length;
if (lineLength > cutLength) {
lastLineText = [lastLineText substringToIndex:(lastLineText.length - cutLength)];
}
[contentText appendString:[NSString stringWithFormat:@"%@.....",lastLineText]];
} else {
[contentText appendString:contents[i]];
}
}
NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
NSDictionary *dictionary = @{
NSForegroundColorAttributeName : self.textColor,
NSFontAttributeName : self.font,
NSParagraphStyleAttributeName : style
};
NSMutableAttributedString *mutableAttribText = [[NSMutableAttributedString alloc] initWithString:[contentText stringByAppendingString:@" 更多"] attributes:dictionary];
[mutableAttribText addAttributes:@{
NSFontAttributeName : [UIFont boldSystemFontOfSize:16.0f],
NSForegroundColorAttributeName : [UIColor blueColor]
} range:NSMakeRange(contentText.length, 4)];
self.attributedText = mutableAttribText;
}
// 获取 Label 每行内容 得到一个数组
- (NSArray *)getLinesArrayOfLabelRows
{
CGFloat labelWidth = self.frame.size.width;
NSString *text = [self text];
UIFont *font = [self font];
if (text == nil) {
return nil;
}
CTFontRef myFont = CTFontCreateWithName(( CFStringRef)([font fontName]), [font pointSize], NULL);
NSMutableAttributedString *attStr = [[NSMutableAttributedString alloc] initWithString:text];
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.lineBreakMode = NSLineBreakByCharWrapping;
[attStr addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, attStr.length)];
[attStr addAttribute:(NSString *)kCTFontAttributeName
value:(__bridge id)myFont
range:NSMakeRange(0, attStr.length)];
CFRelease(myFont);
CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString(( CFAttributedStringRef)attStr);
CGMutablePathRef path = CGPathCreateMutable();
CGPathAddRect(path, NULL, CGRectMake(0,0,labelWidth,100000));
CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, 0), path, NULL);
NSArray *lines = ( NSArray *)CTFrameGetLines(frame);
NSMutableArray *linesArray = [[NSMutableArray alloc]init];
for (id line in lines) {
CTLineRef lineRef = (__bridge CTLineRef )line;
CFRange lineRange = CTLineGetStringRange(lineRef);
NSRange range = NSMakeRange(lineRange.location, lineRange.length);
NSString *lineString = [text substringWithRange:range];
CFAttributedStringSetAttribute((CFMutableAttributedStringRef)attStr,
lineRange,
kCTKernAttributeName,
(CFTypeRef)([NSNumber numberWithFloat:0.0]));
CFAttributedStringSetAttribute((CFMutableAttributedStringRef)attStr,
lineRange,
kCTKernAttributeName,
(CFTypeRef)([NSNumber numberWithInt:0.0]));
[linesArray addObject:lineString];
}
CGPathRelease(path);
CFRelease(frame);
CFRelease(frameSetter);
return (NSArray *)linesArray;
}
@end
调用该方法的的代码：
- (void)viewDidLoad {
[super viewDidLoad];
NSString *context = @"当最后一行显示不全时，需求有时候需要改变省略号的位置，系统并未提供，张娜拉邀请我去她家里玩了一会，然后吃饭，看电视动词打次，然后将最后一行文字在指定的地方截断，再拼接省略号";
NSLog(@" %lu ",(unsigned long)context.length);
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10.0f, 60.0f, self.view.frame.size.width - 20.0f, 70.0f)];
label.font = [UIFont systemFontOfSize:16.0f];
label.numberOfLines = 3;
[self.view addSubview:label];
UITapGestureRecognizer *labelTapGestureRecognizer = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(labelTouchUpInside)];
[label addGestureRecognizer:labelTapGestureRecognizer];
label.text = context;
[label setReadMoreLabelContentMode];
}
-(void)labelTouchUpInside{
NSLog(@"查看更多");
}