Question

我有一个UISegmentedControl来处理温度单位的设置（ºC/ºF）。
它工作正常，但如果用户更改设置，显示的单位将不会更改（刷新自身），除非用户导航到另一个视图控制器，然后返回到相关的视图控制器。

我正在使用

- (void)viewWillAppear:(BOOL)animated
{
//Gets user setting choice for Fahrenheit or Celsius
NSUserDefaults *preferences = [NSUserDefaults standardUserDefaults];
temperatureSetting = [[preferences valueForKey:@"temperature setting"]intValue];
//For getting the current value of temperature from the JSON data
NSInteger temp = [[conditions objectForKey:@"temperature"]intValue];
//For checking the user's setting to display either Fahrenheit or Celsius
if (temperatureSetting == 0) {
    temp = (temp * 1.8) + 32;
    temperatureLabel.text = [NSString stringWithFormat:@"%i°F", temp];
} else {
    temperatureLabel.text = [NSString stringWithFormat: @"%iºC", temp];
}
}


- (IBAction)temperatureSelection:(UISegmentedControl *)sender {
//Used to save settings
NSUserDefaults *temperaturePreference = [NSUserDefaults standardUserDefaults];
//To check which segment is selected and save the value but also remember it
if ([sender selectedSegmentIndex] == 0) {
    [temperaturePreference setInteger:0 forKey:@"temperature setting"];
    [selectedSegment setInteger:0 forKey:@"segment setting"];
} else if ([sender selectedSegmentIndex] == 1) {
    [temperaturePreference setInteger:1 forKey:@"temperature setting"];
    [selectedSegment setInteger:1 forKey:@"segment setting"];
}
//To make sure the setting is saved
[temperaturePreference synchronize];
[selectedSegment synchronize];

}

如何在用户更改后立即更改显示的单位？谢谢！

Answer 1

将viewWillAppear:内的代码移动到单独的方法中。当用户更改设置时调用该方法。

Answer 2

尝试在- (IBAction)temperatureSelection:(UISegmentedControl *)sender方法结束之前添加该行代码。

- (IBAction)temperatureSelection:(UISegmentedControl *)sender{
//..etc
temperatureSetting = [[temperaturePreferences valueForKey:@"temperature setting"]intValue];
if (temperatureSetting == 0) {
 temp = (temp * 1.8) + 32;
 temperatureLabel.text = [NSString stringWithFormat:@"%i°F", temp];
} else {
 temperatureLabel.text = [NSString stringWithFormat: @"%iºC", temp];
}
 [self.view setNeedsDisplayInRect:temperatureLabel.frame];//probably is not needed it forces the view to redraw itself as it mark as dirty
}

用户使用UISegmentedControl更改后立即更改显示的单位

2 个答案: