给UITextView添加链接

给UITextView增加了链接
现在在iOS添加你自己的Twitter账户更加简单了，现在你可以给一个NSAttributedString增加链接了，然后当它被点击的时候唤起一个定制的action。

首先，创建一个NSAttributedString然后增加给它增加一个NSLinkAttributeName 属性，见以下：

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:@"This is an example by @marcelofabri_"];

[attributedString addAttribute:NSLinkAttributeName

value:@"username://marcelofabri_"

range:[[attributedString string] rangeOfString:@"@marcelofabri_"]];

NSDictionary *linkAttributes = @{NSForegroundColorAttributeName: [UIColor greenColor],

NSUnderlineColorAttributeName: [UIColor lightGrayColor],

NSUnderlineStyleAttributeName: @(NSUnderlinePatternSolid)};

// assume that textView is a UITextView previously created (either by code or Interface Builder)

textView.linkTextAttributes = linkAttributes; // customizes the appearance of links

textView.attributedText = attributedString;

textView.delegate = self;

这样就可以让链接在文本中显示。然而，你也可以控制当链接被点击的时候会发生什么，实现这个可以使用UITextViewDelegate协议的新的shouldInteractWithURL方法，就像这样：

- (BOOL)textView:(UITextView *)textView shouldInteractWithURL:(NSURL *)URL inRange:(NSRange)characterRange {

if ([[URL scheme] isEqualToString:@"username"]) {

NSString *username = [URL host];

// do something with this username

// ...

return NO;

}

return YES; // let the system open this URL

}