Timer Change Button title flashing

In a project, use the UIButton to set the countdown to receive SMS verification code, but use Nstimer to set the title will appear continuous flashing problem.

After testing found the content, if it is only a separate setting button Titlelabel content will not show the effect, if you set the title and the status of this
The problem of continuous flashing after using the Nstimer mode

When you need to use two methods at the same time, there will be no flicker problem, that is, both set

_getcodebutton.titlelabel.text = [NSString stringwithformat:@ "acquires%ds again", _second];

[_getcodebutton settitle:[nsstring stringwithformat:@ "Get%ds Again", _second] forstate:uicontrolstatenormal];

Timer Change Button title flashing