iOS 字体下载

 // 创建下载字体请求描述的准备
    NSMutableDictionary *attrs = [NSMutableDictionary dictionaryWithObjectsAndKeys:fontName, kCTFontNameAttribute, nil];
    CTFontDescriptorRef desc = CTFontDescriptorCreateWithAttributes((__bridge CFDictionaryRef)attrs);
    NSMutableArray *descs = [NSMutableArray arrayWithCapacity:0];
    [descs addObject:(__bridge id)desc];
    CFRelease(desc);

    
    //开始下载字体
    __block BOOL errorDuringDownload = NO;
    CTFontDescriptorMatchFontDescriptorsWithProgressHandler( (__bridge CFArrayRef)descs, NULL,  ^(CTFontDescriptorMatchingState state, CFDictionaryRef progressParameter) {
        
        //NSLog( @"state %d - %@", state, progressParameter);
        
        double progressValue = [[(__bridge NSDictionary *)progressParameter objectForKey:(id)kCTFontDescriptorMatchingPercentage] doubleValue];
        
        if (state == kCTFontDescriptorMatchingDidBegin) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                // Show an activity indicator
                [_fActivityIndicatorView startAnimating];
                _fActivityIndicatorView.hidden = NO;
                
                // Show something in the text view to indicate that we are downloading
                _fTextView.text= [NSString stringWithFormat:@"Downloading %@", fontName];
                _fTextView.font = [UIFont systemFontOfSize:14.];
                
                NSLog(@"开始匹配...");
            });
        } else if (state == kCTFontDescriptorMatchingDidFinish) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                // Remove the activity indicator
                [_fActivityIndicatorView stopAnimating];
                _fActivityIndicatorView.hidden = YES;
                
                // Display the sample text for the newly downloaded font
                NSUInteger sampleIndex = [_fontNames indexOfObject:fontName];
                _fTextView.text = [_fontSamples objectAtIndex:sampleIndex];
                _fTextView.font = [UIFont fontWithName:fontName size:24.];
                
                // Log the font URL in the console
                CTFontRef fontRef = CTFontCreateWithName((__bridge CFStringRef)fontName, 0., NULL);
                CFStringRef fontURL = CTFontCopyAttribute(fontRef, kCTFontURLAttribute);
                NSLog(@"%@", (__bridge NSURL*)(fontURL));
                CFRelease(fontURL);
                CFRelease(fontRef);
                
                if (!errorDuringDownload) {
                    NSLog(@"%@ downloaded", fontName);
                }
            });
        } else if (state == kCTFontDescriptorMatchingWillBeginDownloading) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                // Show a progress bar
                _fProgressView.progress = 0.0;
                _fProgressView.hidden = NO;
                NSLog(@"开始下载...");
            });
        } else if (state == kCTFontDescriptorMatchingDidFinishDownloading) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                // Remove the progress bar
                _fProgressView.hidden = YES;
                NSLog(@"下载完成");
            });
        } else if (state == kCTFontDescriptorMatchingDownloading) {
            dispatch_async( dispatch_get_main_queue(), ^ {
                // Use the progress bar to indicate the progress of the downloading
                [_fProgressView setProgress:progressValue / 100.0 animated:YES];
                NSLog(@"下载进度 %.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
            errorDuringDownload = YES;
            
            dispatch_async( dispatch_get_main_queue(), ^ {
                _fProgressView.hidden = YES;
                NSLog(@"下载失败: %@", _errorMessage);
            });
        }
        
        return (bool)YES;
    });