iOS 字符串按宽度截取

//

//  ViewController.m

//  TestSubText

//

//  Created by zhangzifei on 2019/9/20.

//  Copyright © 2019 KYE. All rights reserved.

//

#import "ViewController.h"

#import

@interface ViewController ()

@end

@implementationViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view.

    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(20, 100, 300, 30)];

    label.text = @"创建存结构CoreTextData储B结构CTImgData";

    label.backgroundColor = [UIColor redColor];

    [self.viewaddSubview:label];

    CGFloattextWidth = [selfgetTextWidthWithStr:label.text];

    if(textWidth >300) {

        label.text= [selfgetVisibleStringWithWidth:300font:label.fontstr:label.text];

    }

}

- (CGFloat)getTextWidthWithStr:(NSString*)str {

    NSString*countStr = str;

    NSMutableParagraphStyle *p = [[NSMutableParagraphStyle alloc] init];

    p.lineBreakMode = NSLineBreakByCharWrapping;

    CGFloat countWidht = [countStr boundingRectWithSize:CGSizeMake(999., 25.) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:17.f], NSParagraphStyleAttributeName:p} context:nil].size.width;

    returncountWidht;

}

- (NSString*)getVisibleStringWithWidth:(CGFloat)width font:(UIFont*)font str:(NSString*)str {

    NSMutableParagraphStyle *p = [[NSMutableParagraphStyle alloc] init];

    p.lineBreakMode = NSLineBreakByCharWrapping;

    NSAttributedString *namesAtt = [[NSAttributedString alloc] initWithString:str attributes:@{NSFontAttributeName:font, NSParagraphStyleAttributeName:p}];

    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)namesAtt);

    UIBezierPath *path = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, width, 25.)];

    CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, str.length), path.CGPath, NULL);

    CFRange range = CTFrameGetVisibleStringRange(frame);

    CFRelease(framesetter);

    CFRelease(frame);

    return [str substringWithRange:NSMakeRange(range.location, range.length)];

}

@end