iOS可以动态的为系统下载字体，这些字体都下载到了系统的目录下，并且可以被其他应用公用
来看下如何实现动态下载：
// 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;
});
NSString *ffontName = @"STBaoli-SC-Regular";
UIFont* aFont = [UIFont fontWithName:fontName size:.]; // 判断字体是否已经下载
if (aFont && ([aFont.fontName compare:fontName] == NSOrderedSame || [aFont.familyName compare:fontName] == NSOrderedSame)) {
// 使用已下载的字体
NSUInteger sampleIndex = [_fontNames indexOfObject:fontName];
_fTextView.text = [_fontSamples objectAtIndex:sampleIndex];
_fTextView.font = [UIFont fontWithName:fontName size:.];
return;
}