iOS开发——文本高度

1.简单的计算文本高度 

// 要计算的文本内容
    NSString *testString = @"刘成利，软件工程专业毕业，iOS开发者，目前工作于北京，在证券金融领域从事iOS App开发，由于工作有闲暇时间，所以开始写博客，分享自己浅薄的iOS相关开发经验，希望任何人士多多指正指点或者批评教育。";
    
    UILabel *labeliOS7        = [[UILabel alloc]init];
    labeliOS7.text            = testString;
    labeliOS7.font            = [UIFont systemFontOfSize:17];
    labeliOS7.backgroundColor = [UIColor lightGrayColor];
    labeliOS7.numberOfLines   = 0;
    // 计算高度
    /*
     参数说明：boundingRectWithSize:后面跟随宽度和高度
     */
    CGSize titleSize = [testString boundingRectWithSize:CGSizeMake(300, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:17]} context:nil].size;
    
    labeliOS7.frame  = CGRectMake(20, 300, 300, titleSize.height);
    
    [self.view addSubview:labeliOS7];

2.计算文本高度的工具类（转自我的领头同事:游贤明教授）

//
//  NSString+LabelWidthAndHeight.h
//  ZiPeiYi
//
//  Created by YouXianMing on 15/12/9.
//  Copyright © 2015年 YouXianMing. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface NSString (LabelWidthAndHeight)

/**
 *  Get the string's height with the fixed width.
 *
 *  @param attribute String's attribute, eg. attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:18.f]}
 *  @param width     Fixed width.
 *
 *  @return String's height.
 */
- (CGFloat)heightWithStringAttribute:(NSDictionary <NSString *, id> *)attribute fixedWidth:(CGFloat)width;

/**
 *  Get the string's width.
 *
 *  @param attribute String's attribute, eg. attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:18.f]}
 *
 *  @return String's width.
 */
- (CGFloat)widthWithStringAttribute:(NSDictionary <NSString *, id> *)attribute;

/**
 *  Get a line of text height.
 *
 *  @param attribute String's attribute, eg. attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:18.f]}
 *
 *  @return String's width.
 */
+ (CGFloat)aLineOfTextHeightWithStringAttribute:(NSDictionary <NSString *, id> *)attribute;

@end

//
//  NSString+LabelWidthAndHeight.m
//  ZiPeiYi
//
//  Created by YouXianMing on 15/12/9.
//  Copyright © 2015年 YouXianMing. All rights reserved.
//

#import "NSString+LabelWidthAndHeight.h"

@implementation NSString (LabelWidthAndHeight)

- (CGFloat)heightWithStringAttribute:(NSDictionary <NSString *, id> *)attribute fixedWidth:(CGFloat)width {
    
    NSParameterAssert(attribute);
    
    CGFloat height = 0;
    
    if (self.length) {
        
        CGRect rect = [self boundingRectWithSize:CGSizeMake(width, MAXFLOAT)
                                         options:NSStringDrawingTruncatesLastVisibleLine |NSStringDrawingUsesLineFragmentOrigin |
                       NSStringDrawingUsesFontLeading
                                      attributes:attribute
                                         context:nil];
        
        height = rect.size.height;
    }
    
    return height;
}

- (CGFloat)widthWithStringAttribute:(NSDictionary <NSString *, id> *)attribute {
    
    NSParameterAssert(attribute);
    
    CGFloat width = 0;
    
    if (self.length) {
        
        CGRect rect = [self boundingRectWithSize:CGSizeMake(MAXFLOAT, 0)
                                         options:NSStringDrawingTruncatesLastVisibleLine |NSStringDrawingUsesLineFragmentOrigin |
                       NSStringDrawingUsesFontLeading
                                      attributes:attribute
                                         context:nil];
        
        width = rect.size.width;
    }
    
    return width;
}

+ (CGFloat)aLineOfTextHeightWithStringAttribute:(NSDictionary <NSString *, id> *)attribute {
    
    CGFloat height = 0;
    CGRect rect    = [@"One" boundingRectWithSize:CGSizeMake(200, MAXFLOAT)
                                          options:NSStringDrawingTruncatesLastVisibleLine |NSStringDrawingUsesLineFragmentOrigin |
                      NSStringDrawingUsesFontLeading
                                       attributes:attribute
                                          context:nil];
    
    height = rect.size.height;
    return height;
}

@end