iOS UIFont 的学习与使用

通常,我们使用字体都是系统默认的字体. 有时候从阅读体验,美观度设计师都会考虑用一些更高大尚的字体. 系统字体库给英文各种style的发挥空间很大,但是中文则不然.

但是苹果给使用中文的字体的开发者提供了动态下载字体库的福利,这个真是好,并且下载到/private/var/mobile/Library/Assets/com_apple_MobileAsset_Font/ 这样不会增加app本身的大小. 不失为一种好的选择.

前提: 你首先要知道你要使用的字体的官方名字, 用这个名字当索引下载.

官方竟然有文档和demo 真是方便的不要不要的:

https://developer.apple.com/library/ios/samplecode/DownloadFont/Listings/DownloadFont_ViewController_m.html

操作基本步骤

1. 首先判断是否有这种字体无则用默认的

(如果要使用一些 iOS8,iOS9才有的字体一定要考虑低版本用户的情况,会闪退,在 font 类别里面也要做预判断,没有这个字体就用默认的呗)

+ (UIFont *)normalHfFontWithSize: (CGFloat)fontSize {

    return [UIFont isFontDownloaded:@"FZLTXHK--GBK1-0"] ? [UIFont fontWithName:@"FZLTXHK--GBK1-0" size:fontSize] : [UIFont systemFontWithSize:fontSize];
}

+ (BOOL)isFontDownloaded:(NSString *)fontName {
    UIFont* aFont = [UIFont fontWithName:fontName size:12.0];
    if (aFont && ([aFont.fontName compare:fontName] == NSOrderedSame
                  || [aFont.familyName compare:fontName] == NSOrderedSame)) {
        return YES;
    } else {
        return NO;
    }
}

2. 我的下载策略是打开应用就在父线程里面处理需要的字体下载等事宜 , 也有人是用再下载 ,看需求吧

    Reachability *r = [Reachability reachabilityForInternetConnection];
    [r startNotifier];
    NetworkStatus netStatus = [r currentReachabilityStatus];
    
    NSArray *fonts = @[@"FZLTZHK--GBK1-0",@"FZLTXHK--GBK1-0"];
    
    for (NSString *font in fonts) {
        NSString *isFontAvailable = [[NSUserDefaults standardUserDefaults] objectForKey:[NSString stringWithFormat:@"FontDownloaded%@",font]];
        if ((netStatus == ReachableViaWiFi && ![isFontAvailable isEqualToString:font]) || [isFontAvailable isEqualToString:font]) {
            [UIFont downloadFont:font];
        }
    }


+ (void)downloadFont:(NSString *)fontName {
    
    UIFont* aFont = [UIFont fontWithName:fontName size:12.];
    // If the font is already downloaded
    if (aFont && ([aFont.fontName compare:fontName] == NSOrderedSame || [aFont.familyName compare:fontName] == NSOrderedSame)) {
        // Go ahead and display the sample text.
        return;
    }
    
    // Create a dictionary with the font's PostScript name.


    NSMutableDictionary *attrs = [NSMutableDictionary dictionaryWithObjectsAndKeys:fontName, kCTFontNameAttribute, nil];
    
    // Create a new font descriptor reference from the attributes dictionary.
    CTFontDescriptorRef desc = CTFontDescriptorCreateWithAttributes((__bridge CFDictionaryRef)attrs);
    // 将字体描述对象放到一个NSMutableArray中
    NSMutableArray *descs = [NSMutableArray arrayWithCapacity:0];
    [descs addObject:(__bridge id)desc];
    CFRelease(desc);
    
    __block BOOL errorDuringDownload = NO;
    
    // Start processing the font descriptor..
    // This function returns immediately, but can potentially take long time to process.
    // The progress is notified via the callback block of CTFontDescriptorProgressHandler type.
    // See CTFontDescriptor.h for the list of progress states and keys for progressParameter dictionary.
    CTFontDescriptorMatchFontDescriptorsWithProgressHandler( (__bridge CFArrayRef)descs, NULL,  ^(CTFontDescriptorMatchingState state, CFDictionaryRef progressParameter) {
        
        NSString *errorMessage;

        DLog( @"state %d - %@", state, progressParameter);
        
//        double progressValue = [[(__bridge NSDictionary *)progressParameter objectForKey:(id)kCTFontDescriptorMatchingPercentage] doubleValue];
        
        if (state == kCTFontDescriptorMatchingDidBegin) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                DLog(@"Begin Matching");
            });
        } else if (state == kCTFontDescriptorMatchingDidFinish) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                
                // Log the font URL in the console
                CTFontRef fontRef = CTFontCreateWithName((__bridge CFStringRef)fontName, 0., NULL);
                CFStringRef fontURL = CTFontCopyAttribute(fontRef, kCTFontURLAttribute);
                DLog(@"%@", (__bridge NSURL*)(fontURL));
                CFRelease(fontURL);
                CFRelease(fontRef);
                
                if (!errorDuringDownload) {
                    [[NSUserDefaults standardUserDefaults] setObject:fontName forKey:[NSString stringWithFormat:@"FontDownloaded%@",fontName]];
                    [[NSUserDefaults standardUserDefaults] synchronize];
                    DLog(@"%@ downloaded", fontName);
                }
            });
        } else if (state == kCTFontDescriptorMatchingWillBeginDownloading) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                DLog(@"Begin Downloading");
            });
        } else if (state == kCTFontDescriptorMatchingDidFinishDownloading) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                DLog(@"Finish downloading");
                // 可以在这里修改UI控件的字体
            });
        } else if (state == kCTFontDescriptorMatchingDownloading) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                //DLog(@"Downloading %.0f%% complete", progressValue);
            });
        } else if (state == kCTFontDescriptorMatchingDidFailWithError) {
            // An error has occurred.
            // Get the error message
            NSError *error = [(__bridge NSDictionary *)progressParameter objectForKey:(id)kCTFontDescriptorMatchingError];
            if (error != nil) {
                errorMessage = [error description];
            } else {
                errorMessage = @"ERROR MESSAGE IS NOT AVAILABLE!";
            }
            // Set our flag 设置标志
            errorDuringDownload = YES;
            
            dispatch_async( dispatch_get_main_queue(), ^ {
                DLog(@"Download error: %@", errorMessage);
            });
        }
        return (bool)YES;
    });
}

妥妥的满足使用动态下载的字体需求

备注:

其他方法还有使用字体资源文件(尾缀为.ttf或otf格式文件),上网上搜吧讲解一堆 .

但是这里存在的问题 1 需要把这个 .ttf文件 target到工程不像动态下载不增加应用本身的大小的特点

其次是如果没有处理版权问题,这个就大发了是吧...

看需求正确使用恰当的方法解决问题吧

参考:

http://www.awnlab.com/archives/2658.html

转载于:https://www.cnblogs.com/someonelikeyou/p/5581677.html

iOS UIFont 的学习与使用

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