Your animation speeds up and slows down because it uses the "natural" UIViewAnimationOptionCurveEaseInOut
curve. Use UIViewAnimationOptionCurveLinear
option to use constant speed motion:
[UIView animateWithDuration:2.5f
delay:0
options:UIViewAnimationOptionCurveLinear
animations:^{
CGRect currentFrame=self.image.frame;
currentFrame.origin.x-=10;
[self.image setFrame:currentFrame];
}
completion:^(BOOL finished){
}
];