同时对view延时执行两个动画时候的现象

//
//  ViewController.m
//  ViewAnimation
//
//  Created by YouXianMing on 15/1/13.
//  Copyright (c) 2015年 YouXianMing. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic, strong) UIView   *showView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
 
    // 添加view
    self.showView                 = [[UIView alloc] initWithFrame:CGRectMake(10, 100, 0, 30)];
    self.showView.backgroundColor = [UIColor redColor];
    [self.view addSubview:self.showView];
    
    // 1s后执行变长动画
    [self performSelector:@selector(viewAnimationOne) withObject:nil afterDelay:1];
    
    // 2s后执行缩小动画
    [self performSelector:@selector(viewAnimationTwo) withObject:nil afterDelay:2];
}

- (void)viewAnimationOne {

    // 动画时间长度为3s
    [UIView animateWithDuration:3.f animations:^{
        self.showView.frame = CGRectMake(10, 100, 0 + 300, 30);
    } completion:^(BOOL finished) {
        NSLog(@"动画1结束 %@", NSStringFromCGRect(self.showView.frame));
    }];
    
    
}

- (void)viewAnimationTwo {
    
    // 动画时间长度为1s
    [UIView animateWithDuration:1.f animations:^{
        self.showView.frame = CGRectMake(10, 100, 0, 30);
    } completion:^(BOOL finished) {
        NSLog(@"动画2结束 %@", NSStringFromCGRect(self.showView.frame));
    }];
}


@end