字体下载

1、

//判断字体是否已经下载
-(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;
    }
}


-(void)downloadFont:(NSString *)fontStr
{
    if ([self isFontDownloaded:fontStr]) {
//已经下载过，发送通知 ，UI修改字体
        [[NSUserDefaults standardUserDefaults] setObject:fontStr forKey:@"fontnamekey"];
        [[NSNotificationCenter defaultCenter] postNotificationName:@"fontnamekey" object:self];
        return;
    }
//创建一个字典承装 字体的name postscript
    NSMutableDictionary *attrs = [NSMutableDictionary dictionaryWithObjectsAndKeys:fontStr,kCTFontNameAttribute, nil];
//创建一个字体描述对象
    CTFontDescriptorRef desc = CTFontDescriptorCreateWithAttributes((__bridge CFDictionaryRef)attrs);
//字体描述对象放到数组中    
NSMutableArray *descs = [NSMutableArray arrayWithCapacity:0];
    [descs addObject:(__bridge id)desc];
    CFRelease(desc);
       __block BOOL errorDuringDownload = NO;
//准备好字体描述对象，开始下载字体
       CTFontDescriptorMatchFontDescriptorsWithProgressHandler( (__bridge CFArrayRef)descs, NULL,  ^bool(CTFontDescriptorMatchingState state, CFDictionaryRef _Nonnull progressParameter) {
        
        double progressValue = [[(__bridge NSDictionary *)progressParameter objectForKey:(id)kCTFontDescriptorMatchingPercentage] doubleValue];
        
        if (state == kCTFontDescriptorMatchingDidBegin) {
            NSLog(@" 字体已经开始匹配 ");
        } else if (state == kCTFontDescriptorMatchingDidFinish) {
            if (!errorDuringDownload) {
                NSLog(@" 字体匹配完成 ", fontStr);
            }
        } else if (state == kCTFontDescriptorMatchingWillBeginDownloading) {
            NSLog(@" 字体开始下载 ");
        } else if (state == kCTFontDescriptorMatchingDidFinishDownloading) {
            NSLog(@" 字体下载完成 ");
            dispatch_async( dispatch_get_main_queue(), ^ {
                // 可以在这里修改 UI 控件的字体
                [[NSUserDefaults standardUserDefaults] setObject:fontStr forKey:kFontNameKey];

                [[NSNotificationCenter defaultCenter] postNotificationName:kNotificationFontName object:self];
                
            });
        } else if (state == kCTFontDescriptorMatchingDownloading) {
            NSLog(@" 下载进度 %.0f%% ", progressValue);
        } else if (state == kCTFontDescriptorMatchingDidFailWithError) {
            NSError *error = [(__bridge NSDictionary *)progressParameter objectForKey:(id)kCTFontDescriptorMatchingError];
            if (error != nil) {
                self->_errorMessage = [error description];
            } else {
                self->_errorMessage = @"ERROR MESSAGE IS NOT AVAILABLE!";
            }
            // 设置标志
            errorDuringDownload = YES;
            NSLog(@" 下载错误: %@", self->_errorMessage);
        }
        
        return (BOOL)YES;
    });
}

参考链接：http://blog.devtang.com/2013/08/11/ios-asian-font-download-introduction/
注意：打包报错： Incompatible block pointer types passing 'BOOL (^)(CTFontDescriptorMatch，使用这个方法：

CTFontDescriptorMatchFontDescriptorsWithProgressHandler( (__bridge CFArrayRef)descs, NULL,  ^bool(CTFontDescriptorMatchingState state, CFDictionaryRef _Nonnull progressParameter)