Ios UILabel文本在显示文件进度文本时闪烁

我在标签中显示文件传输进度。但是当出现

fileprogress

数据字符串时，会根据其位置闪烁

directionstring

文本。如何停止附加字符串的闪烁

directionstring = @"uploaging file";
fileprogress = transferring rate EX.(25.00 MB of 50.00 MB);
message = [message stringByAppendingString:[NSString stringWithFormat:@"%@%@",fileprogress,directionstring]];
progressLabel.text = message;

我做了一个例子（用定时器模拟进度），测试它，文本不闪烁

@implementation ViewController
{
    IBOutlet UILabel *_progressLabel;
    NSInteger _percent;
}

- (void)showProgress
{
    _percent = 0;

    [NSTimer scheduledTimerWithTimeInterval:0.2
                                     target:self
                                   selector:@selector(updateProgress:)
                                   userInfo:nil
                                    repeats:YES];
}

- (void)updateProgress:(NSTimer *)timer {
    NSString *directionstring = @" uploading file";
    NSString *fileprogress = [NSString stringWithFormat:@"%ld of 100", (long)_percent++];
    NSString *message = [NSString stringWithFormat:@"%@%@", fileprogress, directionstring];
    _progressLabel.text = message;
}

@end

我做了一个例子（用定时器模拟进度），测试它，文本不闪烁

@implementation ViewController
{
    IBOutlet UILabel *_progressLabel;
    NSInteger _percent;
}

- (void)showProgress
{
    _percent = 0;

    [NSTimer scheduledTimerWithTimeInterval:0.2
                                     target:self
                                   selector:@selector(updateProgress:)
                                   userInfo:nil
                                    repeats:YES];
}

- (void)updateProgress:(NSTimer *)timer {
    NSString *directionstring = @" uploading file";
    NSString *fileprogress = [NSString stringWithFormat:@"%ld of 100", (long)_percent++];
    NSString *message = [NSString stringWithFormat:@"%@%@", fileprogress, directionstring];
    _progressLabel.text = message;
}

@end

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您可能正在重新绘制标签@pskyou可能正在重新画标签@psk