what does it all mean?
While trying to implement a way to find if a string is empty (truly empty, nil (aka null) or filled with whitespaces) I bumped into a neat solution @ http://stackoverflow.com/questions/3436173/nsstring-is-empty
// Returns YES if the string is nil or equal to @""
{
// Note that [string length] == 0 can be false
// when [string // isEqualToString:@""] is true, because these are Unicode strings.
if (((NSNull *) string == [NSNull null]) || (string == nil) ) {
return YES;
}
string = [string stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]];
if ([string isEqualToString:@""]) {
return YES;
}
return NO;
}
But what sparked up a thought here was that they were using + ClassMethod , and many times while I'm digging around for a solution many are simply -intanceMethods
so what does that mean? One way to think about it, is if I made the above function
an -instance method, then I would call it in my solution like this:
bool boolResult = [self isEmptyString:myStringVariable];
in a +class method I create a new class (.h and .m files)
in my header:
#import <Foundation/Foundation.h>
@interface NSString (AdditionalStringFunctions)
+ (BOOL)isEmptyString:(NSString *)string;
@end
in my implementation I added the function:
#import "NSString+AdditionalStringFunctions.h"
@implementation NSString (AdditionalStringFunctions)
+ (BOOL) stringIsEmpty:(NSString *) aString {
if ((NSNull *) aString == [NSNull null]) {
return YES;
}
if (aString == nil) {
return YES;
} else if ([aString length] == 0) {
return YES;
} else {
aString = [aString stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]];
if ([aString length] == 0) {
return YES;
}
}
return NO;
}
@end
Now I get to use it like this:
NSString *myString = [[NSString alloc] init];
myString = @"SomeString";
if([NSString stringIsEmpty:myString]) {
NSLog(@"Your String is empty!");
}
else{
NSLog(@"Your String is NOT empty!");
}
I'll take some time later to look into how to make it be more usable something like:
[myString isStringEmpty]; sort of like the length function
