CODEWITHSUNDEEP
iphoneobjective-cios
Ned
Ned

Reputation: 6270

Assignment causes unexpected results with specific iOS configurations

I'm getting some really weird behavior in my iOS app. It works fine on the simulator and on new hardware, but when I test it with the Release configuration on an older-gen iPod Touch (software version 4.2.1) it doesn't work properly. This is my code to drag the object (a UIView subclass):

- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event 
{
UITouch *touch = [touches anyObject];
CGPoint touchPoint = [touch locationInView:self.superview];

// Set the correct center when touched 
touchPoint.x -= deltaX;
touchPoint.y -= deltaY;

NSLog(@"Touch moved1: %f %f, %f %f", touchPoint.x, touchPoint.y, self.center.x, self.center.y);
self.center = touchPoint;
NSLog(@"Touch moved2: %f %f, %f %f\n", touchPoint.x, touchPoint.y, self.center.x, self.center.y);
}

This is the resulting log output:

Touch moved1: -43.000000 45.000000, 45.000000 41.000000
Touch moved2: 45.000000 45.000000, 45.000000 41.000000
Touch moved1: -44.000000 45.000000, 45.000000 41.000000
Touch moved2: 45.000000 45.000000, 45.000000 41.000000

As you can see, somehow the assignment self.center = touchPoint changes the value of touchPoint. Instead of following your finger as you drag, the x and y values touchPoint become equal to the touchPoint.y, which contrains the movement to that diagonal. Any suggestions?

Upvotes: 1

Views: 64

Answers (1)

EricS
EricS

Reputation: 9768

Is the device an ARM6 device?

There is a known bug in the ARM6 code generation in some versions of Xcode that causes problems like this. Try turning on the -mno-thumb option in the "other c flags" build setting section and see if it helps. If so, you can conditionally turn it on for ARM6 builds only.

See: This item

Upvotes: 1

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