Autolayout手写代码实现动画效果。

虽然使用Autolayout用了很久，但是都是在XIB和Storyboard上直接拖拽的约束。

对于一些要自定义的view的视图和动画就很难过了，之前一直在网上搜了很多都没有弄明白。最近查了好久总算实现了一个简单的动画。

背景：在xib或storyboard上拖拽一个UIButton，设置约束为水平居中+垂直居中+宽度100+高度100。

实现效果：点击按钮动画将这个按钮移动到，左边距50+上边距50+宽度100+高度100，再点击移动到，左边距150+上边距150+宽度100+高度100，可反复点击。

实现思路：删除在xib上拖拽的约束，如果不删除，控制台会给出约束冲突的提示。新定义约束给予赋值，注意每次赋值新的约束前需要将原有的约束删除，否则还是会提示约束冲突。

//
//  MyTreeViewController.m
//  LemonTree2
//
//  Created by wdl on 14-10-8.
//  Copyright (c) 2014年 wdl. All rights reserved.
//

@interface MyTreeViewController ()

@property(nonatomic,weak)IBOutlet UIButton *buttonAnimation;
@property(nonatomic,weak)IBOutlet NSLayoutConstraint *cs1;
@property(nonatomic,weak)IBOutlet NSLayoutConstraint *cs2;
@property(nonatomic,strong) NSMutableArray *csArray;
@property(nonatomic,assign) BOOL boolButtonAnimation;

@end

@implementation MyTreeViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    [self.view setBackgroundColor:[UIColor icebergColor]];
    self.navigationController.navigationBarHidden = YES;
    self.csArray = [NSMutableArray arrayWithCapacity:0];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(IBAction)animationButtonPress:(id)sender{
    //删除相关的约束
    [self.view removeConstraint:self.cs1];
    [self.view removeConstraint:self.cs2];
    [self.view removeConstraints:self.csArray];
    [self.csArray removeAllObjects];
    if (!self.boolButtonAnimation) {
        [UIView transitionWithView:self.buttonAnimation
                          duration:1.0
                           options:UIViewAnimationOptionTransitionFlipFromTop
                        animations:^{
                            [self.buttonAnimation setTranslatesAutoresizingMaskIntoConstraints:NO];
                            NSDictionary *viewsDictionary = @{@"buttonAnimation":self.buttonAnimation};
                            [self.csArray addObjectsFromArray:[NSLayoutConstraint
                                                               constraintsWithVisualFormat:@"H:|-50-[buttonAnimation(100)]"
                                                               options:0
                                                               metrics:nil
                                                               views:viewsDictionary]];
                            [self.csArray addObjectsFromArray:[NSLayoutConstraint
                                                               constraintsWithVisualFormat:@"V:|-50-[buttonAnimation(100)]"
                                                               options:0
                                                               metrics:nil
                                                               views:viewsDictionary]];
                            [self.view addConstraints:self.csArray];
                            [self.buttonAnimation layoutIfNeeded];
                        } completion:^(BOOL finished) {
                            self.boolButtonAnimation = YES;
                        }];
    } else {
        [UIView transitionWithView:self.buttonAnimation
                          duration:1.0
                           options:UIViewAnimationOptionTransitionFlipFromTop
                        animations:^{
                            [self.buttonAnimation setTranslatesAutoresizingMaskIntoConstraints:NO];
                            NSDictionary *viewsDictionary = @{@"buttonAnimation":self.buttonAnimation};
                            [self.csArray addObjectsFromArray:[NSLayoutConstraint
                                                               constraintsWithVisualFormat:@"H:|-150-[buttonAnimation(100)]"
                                                               options:0
                                                               metrics:nil
                                                               views:viewsDictionary]];
                            [self.csArray addObjectsFromArray:[NSLayoutConstraint
                                                               constraintsWithVisualFormat:@"V:|-150-[buttonAnimation(100)]"
                                                               options:0
                                                               metrics:nil
                                                               views:viewsDictionary]];
                            [self.view addConstraints:self.csArray];
                            [self.buttonAnimation layoutIfNeeded];
                        } completion:^(BOOL finished) {
                            self.boolButtonAnimation = NO;
                        }];
    }
}

@end