我想在iOS 6中使用约束,并希望将标签与另一个对齐。一个标签和约束是在一个按钮上点击动态创建的。这是一个非常简单的例子,但我得到一个有线错误,我不知道是什么原因。iOS 6自动布局约束错误:“东西是零”
的代码:
- (IBAction)addToLog:(UIButton *)sender {
UILabel *labelLastTime = [[UILabel alloc]initWithFrame:CGRectMake(20, 359, 92, 42)];
labelLastTime.text = [NSString stringWithFormat:@"%@kg x %@", self.selectedPickerWeight, self.selectedPickerRepetitions];
labelLastTime.font = [UIFont boldSystemFontOfSize:17.0];
labelLastTime.textAlignment = NSTextAlignmentCenter;
labelLastTime.textColor = [UIColor colorWithRed:133.0/255.0 green:133.0/255.0 blue:133.0/255.0 alpha:1.0];
labelLastTime.backgroundColor = [UIColor colorWithRed:228.0/255.0 green:228.0/255.0 blue:228.0/255.0 alpha:1.0];
labelLastTime.layer.borderColor = [UIColor colorWithRed:185.0/255.0 green:185.0/255.0 blue:185.0/255.0 alpha:1.0].CGColor;
labelLastTime.layer.borderWidth = 1;
labelLastTime.layer.cornerRadius = 5;
[self.view setTranslatesAutoresizingMaskIntoConstraints:NO];
[self.view addSubview:labelLastTime];
NSLayoutConstraint *cn = [NSLayoutConstraint constraintWithItem:labelLastTime
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.labelTodayVsLastTime
attribute:NSLayoutFormatAlignAllBottom
multiplier:1.0
constant:5.0];
[self.view addConstraint:cn];
}
的错误:
终止应用程序由于未捕获的异常 'NSInvalidArgumentException',原因:“无法在descriptionForLayoutAttribute_layoutItem_coefficient创建描述。东西是零'
当我应用约束,而不是当我设置它时发生错误。我已经设置断点之前
[self.view addConstraint:cn]
,当我检查的结果,我得到零值,这4
container, markerAndPositiveExtraVar, negativeExtraVar and _flange
你检查过以确保self.labelTodayVsLastTime有效吗?我*想*第二个属性是系数? – Padin215