iOS 计算字符串的高度类

#import <Foundation/Foundation.h>

@interface StringHeight : NSObject

+ (CGFloat)heightWithText:(NSString *)text font:(UIFont *)font constrainedToWidth:(CGFloat)width;

@end

#import "StringHeight.h"

#import <CoreText/CoreText.h>

@implementation StringHeight

+ (CGFloat)heightWithText:(NSString *)text font:(UIFont *)font constrainedToWidth:(CGFloat)width

{

    

    if (!text) {

        

        return 0.0;

    }

    // Get text

    CFMutableAttributedStringRef attrString =CFAttributedStringCreateMutable(kCFAllocatorDefault,0);

    CFAttributedStringReplaceString (attrString,CFRangeMake(0,0), (CFStringRef) text);

    CFIndex stringLength = CFStringGetLength((CFStringRef) attrString);

    

    // Change font

    CTFontRef ctFont = CTFontCreateWithName((__bridge CFStringRef) font.fontName, font.pointSize,NULL);

    CFAttributedStringSetAttribute(attrString, CFRangeMake(0, stringLength), kCTFontAttributeName, ctFont);

    

    // Calc the size

    CTFramesetterRef framesetter =CTFramesetterCreateWithAttributedString(attrString);

    CFRange fitRange;

    CGSize frameSize = CTFramesetterSuggestFrameSizeWithConstraints(framesetter, CFRangeMake(0, stringLength), NULL, CGSizeMake(width, CGFLOAT_MAX), &fitRange);

    CFRelease(ctFont);

    CFRelease(framesetter);

    CFRelease(attrString);

    //NSLog(@"frameSize=======:%f", frameSize.height);

    return frameSize.height;

}

@end