// 初始化

POPBasicAnimation *anim = [POPBasicAnimation animation];
 // 限时 1s
 anim.duration = 3.0;
 POPAnimatableProperty * prop = [POPAnimatableProperty propertyWithName:@"count++" initializer:^(POPMutableAnimatableProperty *prop) {
     prop.readBlock = ^(id obj, CGFloat values[]){ values[0] = [[obj description] floatValue]; };
     prop.writeBlock = ^(id obj, const CGFloat values[])
     {
         [obj setText:[NSString stringWithFormat:@"%.2f",values[0]]];
     }
     prop.threshold = 0.01;
 }];
 anim.property = prop;
 anim.fromValue = @(0.0);
 anim.toValue = @(1314.52);
 [self.xt_countLabel pop_addAnimation:anim forKey:@"counting"];