How do I check if NSString is null in Objective-C?
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How do I check if NSString is null in Objective-C?
So to check against NSNull one can either use: if ((NSNull *)getCaption == [NSNull null]) ……In Objective-C:
- nil (all lower-case) is a null pointer to an Objective-C object.
- Nil (capitalized) is a null pointer to an Objective-C class.
- NULL (all caps) is a null pointer to anything else (C pointers, that is).
How does Objective-C handle null values?
The NULL value for Objective-C objects (type id) is nil. While NULL is used for C pointers (type void *). nil = (all lower-case) is a null pointer to an Objective-C object. Nil = (capitalized) is a null pointer to an Objective-C class.
How do I check if a string is empty in Objective C?
If you treat it is a null string like nil , then test (object. length == 0) . object. length will return 0 if object == nil , so this test covers nil objects and strings with length 0.
How do you check if a pointer is NULL?
Use Pointer Value as Condition to Check if Pointer Is NULL in C++ Null pointers are evaluated as false when they are used in logical expressions. Thus, we can put a given pointer in the if statement condition to check if it’s null.
How do I append to NSString?
The format specifier “\%@” is used to insert string values. The example below uses a combination of whitespace and \%@ format specifiers to append two strings to string1: NSString * string3 = [string1 stringByAppendingFormat:@” \%@ \%@”, string2, @”A third string.
How do I check if a value is null in Objective C?
length == 0) . object. length will return 0 if object == nil , so this test covers nil objects and strings with length 0. If you treat a string of length 0 different from a nil string, just check if object == nil .
Is null Objective C?
In Objective-C, there are a few different varieties of nothing: NULL , nil , Nil , and NSNull ….nil / Nil / NULL / NSNull.
| Symbol | Value | Meaning |
|---|---|---|
| nil | (id)0 | literal null value for Objective-C objects |
| Nil | (Class)0 | literal null value for Objective-C classes |
How do you insert a null check?
Use “==” to check a variable’s value. If you set a variable to null with “=” then checking that the variable is equal to null would return true. variableName == null; You can also use “!= ” to check that a value is NOT equal.