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I have an NSArray of CalEvents returned with the [CalCalendarStore eventPredicateWithStartDate] method. From the events returned, I am trying to keep only those in which the title of the event == @"on call" (case-insensitive). I am able to keep in the array those events whose title includes @"on call" with the following code (where 'events' is a 'NSArray' populated with CalEvents ): NSPredicate *onCallPredicate = [NSPredicate predicateWithFormat:@"(SELF.title CONTAINS[c] 'on call')"]; [events filteredArrayUsingPredicate:onCallPredicate]; I've tried using a predicate format string like: @"SELF

This question already has an answer here: How to add percent sign to NSString 7 answers How can I add a percent to my stringWithFormat function? For example, I'd like to have the following: float someFloat = 40.233f; NSString *str = [NSString stringWithFormat:@"%.02f%",someFloat]; This should cause the string to be: 40.23% But it is not the case. How can I achieve this? % being the character beginning printf-style formats, it simply needs to be doubled: float someFloat = 40.233f; NSString *str = [NSString stringWithFormat:@"%.02f%%",someFloat]; spolu The escape code for a percent sign is “%%”,

Whenever I need to create a new NSString variable I always alloc and init it. It seems that there are times when you don't want to do this. How do you know when to alloc and init an NSString and when not to? Whenever I need to create a new NSString variable I always alloc and init it. No, that doesn't make sense. The variable exists from the moment the program encounters the point where you declare it: NSString *myString; This variable is not an NSString. It is storage for a pointer to an NSString. That's what the * indicates: That this variable holds a pointer. The NSString object exists only

When I try to get my keyChain value, it return a string containing: Optional("[thing in the KeyChain]") so, I tried to remove "Optional" by using a loop: var str = KeychainService.loadToken() for(var i = 0; i < 9 ; i++) { str[i] = "" } But i get a error: NSString does not have a member named 'subscript' The KeychainService class: import Foundation import Security let serviceIdentifier = "MySerivice" let userAccount = "authenticatedUser" let accessGroup = "MySerivice" // Arguments for the keychain queries let kSecClassValue = kSecClass.takeRetainedValue() as NSString let kSecAttrAccountValue =