UsingBlocksAsContextInfo/UsingBlocksAsContextInfoAppDelegate.m
/* |
File: UsingBlocksAsContextInfoAppDelegate.m |
Abstract: The sample's application delegate used to manage its primary window and for showing how to use the NSAlert. |
Version: 1.1 |
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*/ |
#import "UsingBlocksAsContextInfoAppDelegate.h" |
@implementation UsingBlocksAsContextInfoAppDelegate |
// This is a quick tip on how to use the context info as a block parameter. |
// You can use this type of pattern for any methods that have a delegate/selector/contextInfo pattern. |
// |
- (IBAction)btnShowAlertClicked:(id)sender { |
NSAlert *alert = [NSAlert alertWithMessageText:@"Alert Message" |
defaultButton:@"Default Button" |
alternateButton:@"Alternate Button" |
otherButton:@"Other Button" |
informativeTextWithFormat:@"Informative Text"]; |
BOOL someLocalVariable = YES; |
// We create a block that can easily access local variables to this method. |
// This is much easier than trying to package them all up into a contextInfo object |
void (^blockCallback)(NSInteger) = ^(NSInteger returnCode) { |
// Inside the block callback we can easily access locals |
if (someLocalVariable) { |
if (returnCode == NSAlertDefaultReturn) { |
[self.button setTitle:@"Default Return Button Clicked!"]; |
} else { |
[self.button setTitle:@"Something else clicked...try again."]; |
} |
} |
}; |
// We copy the block, since it needs to stay alive for longer than the current scope |
[alert beginSheetModalForWindow:self.window |
modalDelegate:[self class] |
didEndSelector:@selector(alertDidEnd:returnCode:contextInfo:) |
contextInfo:(void *)CFBridgingRetain([blockCallback copy])]; |
} |
+ (void)alertDidEnd:(NSAlert *)alert returnCode:(NSInteger)returnCode contextInfo:(void (^)(NSInteger returnCode))continuationHandler { |
continuationHandler(returnCode); |
// The block must always be retained before the first call. This is the matching release |
} |
- (BOOL)applicationShouldTerminateAfterLastWindowClosed:(NSApplication *)sender { |
return YES; |
} |
@end |
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