计算一行文本的高度

计算一行文本的高度

说明

有时候我们需要知道指定的几行文本的高度，此工具用于解决此种问题。

源码

//
//  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

细节