{NSDecimalNumber integerValue} behaving strangely in iOS8

Question

OK team, this is weird. [NSDecimalNumber integerValue] is behaving strangely.

I\'m sat at a breakpoint, trying to figure out why some parts of my app are broken in i

Answer 1

You can use use intValue or unsignedIntValue just fine, but NOT integerValue or unsignedIntegerValue. Here is a unit test that demonstrates the issue, showing that it's related to numbers requiring more than 64 bits of precision:

//
//  NSDecimalNumberBugTests.m
//
//  Created by Lane Roathe on 6/1/17.
//  For Quicken, Inc.
//

#import 

@interface NSDecimalNumberBugTests : XCTestCase

@end

@implementation NSDecimalNumberBugTests

- (void)setUp {
    [super setUp];
    // Put setup code here. This method is called before the invocation of each test method in the class.
}

- (void)tearDown {
    // Put teardown code here. This method is called after the invocation of each test method in the class.
    [super tearDown];
}

- (void)testBug {
    // Use XCTAssert and related functions to verify your tests produce the correct results.
    NSDecimalNumber* decimalLength;
    NSUInteger interval;

    // Start with a number that requires 65+ bits

    // This FAILS (interval is zero)
    decimalLength = [NSDecimalNumber decimalNumberWithString:@"1.8446744073709551616"];
    interval = decimalLength.unsignedIntegerValue;
    XCTAssert(interval == 1);

    // This Works, interval is 1
    interval = decimalLength.unsignedIntValue;
    XCTAssert(interval == 1);

    // Now test with a number that fits in 64 bits

    // This WORKS (interval is 1)
    decimalLength = [NSDecimalNumber decimalNumberWithString:@"1.8446744073709551615"];
    interval = decimalLength.unsignedIntegerValue;
    XCTAssert(interval == 1);
}

@end