小弟最近开发应用时，开始尝试着使用代码来编写界面（之前都是使用的IB），结果在iOS6和iOS7两台机子上却出现了差距有点大的界面效果，如下图：
关键是上面那个button的位置不是我想要的。
两台都是iPhone4
loadview的代码如下：
self.view = [UIView alloc] initWithFrame:[UIScreen mainScreen] bounds]] autorelease];
self.view.backgroundColor = [UIColor whiteColor];
self.recordButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[self.recordButton setTitle:@"Record" forState:UIControlStateNormal];
[self.recordButton addTarget:self action:@selector(PushAppList) forControlEvents:UIControlEventTouchUpInside];
[self.recordButton setBackgroundColor:[UIColor blueColor]];
self.recordButton.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:self.recordButton];
self.playButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[self.playButton setTitle:@"Play" forState:UIControlStateNormal];
[self.playButton addTarget:self action:@selector(PushScriptList) forControlEvents:UIControlEventTouchUpInside];
[self.playButton setBackgroundColor:[UIColor blueColor]];
self.playButton.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:self.playButton];
NSLayoutConstraint *recordButton_contraint_v = [NSLayoutConstraint constraintWithItem:self.recordButton attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1.0f constant:0];
NSLayoutConstraint *recordButton_contraint_h = [NSLayoutConstraint constraintWithItem:self.recordButton attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTop multiplier:1.0f constant:60];
NSLayoutConstraint *playButton_contraint_v = [NSLayoutConstraint constraintWithItem:self.playButton attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1.0f constant:0];
NSLayoutConstraint *playButton_contraint_h = [NSLayoutConstraint constraintWithItem:self.playButton attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeBottom multiplier:1.0f constant:-80.0f];
NSLayoutConstraint *playButton_contraint_width = [NSLayoutConstraint constraintWithItem:self.playButton attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self.recordButton attribute:NSLayoutAttributeWidth multiplier:1.0f constant:0];
[self.view addConstraints:@[recordButton_contraint_v,recordButton_contraint_h,playButton_contraint_h,playButton_contraint_v,playButton_contraint_width]]
就说上面的那个button，我设置的垂直方向的Constraint是离self.view的顶部的距离为60，但是iOS6和iOS7上，第一个button离顶部的距离明显是不同的