App crash if use NSMutableArray instead of NSArray

Question

plot2.graphPoints = graphPointsMutableArray;
//    plot2.graphPoints = @[LMGraphPointMake(CGPointMake(1, 25), @"1", @"34.5")];

If i assign plot2.graphPoints directly an NSArray it is working fine like in the line #2, but if i assign it a NSMutableArray like in the first shown above, the application gives me SIGABRT with the following exception shown below

2018-12-04 02:53:18.079192+0500 ****[10946:258059] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSSingleObjectArrayI point]: unrecognized selector sent to instance 0x60400001f8a0'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000011020c1cb __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010f720f41 objc_exception_throw + 48
    2   CoreFoundation                      0x000000011028c914 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
    3   CoreFoundation                      0x000000011018f178 ___forwarding___ + 1432
    4   CoreFoundation                      0x000000011018eb58 _CF_forwarding_prep_0 + 120
    5   Fandex                              0x000000010e144823 -[LMLineGraphView drawPlots] + 1939
    6   Fandex                              0x000000010e13d678 -[LMLineGraphView drawRect:] + 312
    7   UIKit                               0x0000000111f75c49 -[UIView(CALayerDelegate) drawLayer:inContext:] + 487
    8   QuartzCore                          0x0000000111b380d8 -[CALayer drawInContext:] + 267
    9   QuartzCore                          0x0000000111a4b6cf CABackingStoreUpdate_ + 254
    10  QuartzCore                          0x0000000111b3e1dd ___ZN2CA5Layer8display_Ev_block_invoke + 44
    11  QuartzCore                          0x0000000111b37b34 -[CALayer _display] + 1701
    12  QuartzCore                          0x0000000111ac521f _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 655
    13  QuartzCore                          0x0000000111af0a14 _ZN2CA11Transaction6commitEv + 500
    14  QuartzCore                          0x0000000111af1760 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 76
    15  CoreFoundation                      0x00000001101aedb7 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
    16  CoreFoundation                      0x00000001101aed0e __CFRunLoopDoObservers + 430
    17  CoreFoundation                      0x0000000110193324 __CFRunLoopRun + 1572
    18  CoreFoundation                      0x0000000110192a89 CFRunLoopRunSpecific + 409
    19  GraphicsServices                    0x0000000116ef29c6 GSEventRunModal + 62
    20  UIKit                               0x0000000111ea523c UIApplicationMain + 159
    21  Fandex                              0x000000010e1c7aff main + 111
    22  libdyld.dylib                       0x0000000115336d81 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

This is how i am adding object in NSMutableArray

NSMutableArray *graphPointsMutableArray = [[NSMutableArray alloc] init];
[graphPointsMutableArray addObject:@[LMGraphPointMake(CGPointMake(1, 25), @"1", @"34.5")]];

score 3 · Accepted Answer · answered Dec 03 '18 at 22:11

Your two lines are not equivalent.

This:

 plot2.graphPoints = @[LMGraphPointMake(CGPointMake(1, 25), @"1", @"34.5")];

Assigns an NSArray containing a single LMGraphPoint to plot2.graphPoints

while this:

[graphPointsMutableArray addObject:@[LMGraphPointMake(CGPointMake(1, 25), @"1", @"34.5")]];
plot2.graphPoints = graphPointsMutableArray;

Assigns an NSMutableArray containing an NSArray containing a single LMGraphPoint to plot2.graphPoints

You want

[graphPointsMutableArray addObject:LMGraphPointMake(CGPointMake(1, 25), @"1", @"34.5")];

ie. remove the @[] array literal.

App crash if use NSMutableArray instead of NSArray

1 Answers1