/* |
File: LaunchMeAppDelegate.m |
Abstract: The application's delegate class. Handles incoming |
URL requests. |
Version: 1.7 |
|
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The Apple Software is provided by Apple on an "AS IS" basis. APPLE |
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Copyright (C) 2013 Apple Inc. All Rights Reserved. |
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*/ |
|
#import "LaunchMeAppDelegate.h" |
#import "RootViewController.h" |
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@implementation LaunchMeAppDelegate |
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// ------------------------------------------------------------------------------- |
// application:openURL:sourceApplication:annotation: |
// ------------------------------------------------------------------------------- |
- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation |
{ |
// You should be extremely careful when handling URL requests. |
// Take steps to validate the URL before handling it. |
|
// Check if the incoming URL is nil. |
if (!url) |
return NO; |
|
// Invoke our helper method to parse the incoming URL and extact the color |
// to display. |
UIColor *launchColor = [self extractColorFromLaunchURL:url]; |
// Stop if the url could not be parsed. |
if (!launchColor) |
return NO; |
|
// Assign the created color object a the selected color for display in |
// RootViewController. |
[(RootViewController*)self.window.rootViewController setSelectedColor:launchColor]; |
|
// Update the UI of RootViewController to notify the user that the app was launched |
// from an incoming URL request. |
[[(RootViewController*)self.window.rootViewController urlFieldHeader] setText:@"The app was launched with the following URL"]; |
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return YES; |
} |
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// ------------------------------------------------------------------------------- |
// extractColorFromLaunchURL: |
// Helper method that parses a URL and returns a UIColor object representing |
// the first HTML color code it finds or nil if a valid color code is not found. |
// This logic is specific to this sample. Your URL handling code will differ. |
// ------------------------------------------------------------------------------- |
- (UIColor*)extractColorFromLaunchURL:(NSURL*)url |
{ |
// Hexadecimal color codes begin with a number sign (#) followed by six |
// hexadecimal digits. Thus, a color in this format is represented by |
// three bytes (the number sign is ignored). The value of each byte |
// corresponds to the intensity of either the red, blue or green color |
// components, in that order from left to right. |
// Additionally, there is a shorthand notation with the number sign (#) |
// followed by three hexadecimal digits. This notation is expanded to |
// the six digit notation by doubling each digit: #123 becomes #112233. |
|
|
// Convert the incoming URL into a string. The '#' character will be percent |
// escaped. That must be undone. |
NSString *urlString = [[url absoluteString] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; |
// Stop if the conversion failed. |
if (!urlString) |
return nil; |
|
// Create a regular expression to locate hexadecimal color codes in the |
// incoming URL. |
// Incoming URLs can be malicious. It is best to use vetted technology, |
// such as NSRegularExpression, to handle the parsing instead of writing |
// your own parser. |
NSError *error = nil; |
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"#[0-9a-f]{3}([0-9a-f]{3})?" |
options:NSRegularExpressionCaseInsensitive |
error:&error]; |
|
// Check for any error returned. This can be a result of incorrect regex |
// syntax. |
if (error) |
{ |
NSLog(@"%@", error); |
return nil; |
} |
|
// Extract all the matches from the incoming URL string. There must be at least |
// one for the URL to be valid (though matches beyond the first are ignored.) |
NSArray *regexMatches = [regex matchesInString:urlString options:0 range:NSMakeRange(0, urlString.length)]; |
if (regexMatches.count < 1) |
return nil; |
|
// Extract the first matched string |
NSString *matchedString = [urlString substringWithRange:[regexMatches[0] range]]; |
|
// At this point matchedString will look similar to either #FFF or #FFFFFF. |
// The regular expression has guaranteed that matchedString will be no longer |
// than seven characters. |
|
// Extract an ASCII c string from matchedString. The '#' character should not be |
// included. |
const char *matchedCString = [[matchedString substringFromIndex:1] cStringUsingEncoding:NSASCIIStringEncoding]; |
|
// Convert matchedCString into an integer. |
unsigned long hexColorCode = strtoul(matchedCString, NULL, 16); |
|
CGFloat red, green, blue; |
|
if (matchedString.length-1 > 3) |
// If the color code is in six digit notation... |
{ |
// Extract each color component from the integer representation of the |
// color code. Each component has a value of [0-255] which must be |
// converted into a normalized float for consumption by UIColor. |
red = ((hexColorCode & 0x00FF0000) >> 16) / 255.0f; |
green = ((hexColorCode & 0x0000FF00) >> 8) / 255.0f; |
blue = (hexColorCode & 0x000000FF) / 255.0f; |
} |
else |
// The color code is in shorthand notation... |
{ |
// Extract each color component from the integer representation of the |
// color code. Each component has a value of [0-255] which must be |
// converted into a normalized float for consumption by UIColor. |
red = (((hexColorCode & 0x00000F00) >> 8) | ((hexColorCode & 0x00000F00) >> 4)) / 255.0f; |
green = (((hexColorCode & 0x000000F0) >> 4) | (hexColorCode & 0x000000F0)) / 255.0f; |
blue = ((hexColorCode & 0x0000000F) | ((hexColorCode & 0x0000000F) << 4)) / 255.0f; |
} |
|
// Create and return a UIColor object with the extracted components. |
return [UIColor colorWithRed:red green:green blue:blue alpha:1.0f]; |
} |
|
@end |
