可可自動佈局約束 - 可變數量的視圖的編程填充

Question

我希望能夠將新的視圖添加到超級視圖，但它們保持彼此之間的恆定垂直距離。爲此，我嘗試以編程方式爲每個視圖設置約束，但我無法弄清楚如何去做。問題是我不知道視圖的數量或相對位置。

有沒有一種方法可以爲每個視圖編程設置一個約束，以便不管其他視圖是否與其相鄰，自動佈局會保持視圖之間的恆定間距？

Answer 1

可能這短短的代碼片段是你在找什麼：

NSMutableArray* newVerticalConstraints = [NSMutableArray array]; 
UIView* firstView = nil; 
UIView* secondView = nil; 
UIView* superview = <Your container view>; 
NSArray* subviews = [superview subviews]; 
if ([subviews count] > 0) { 
    firstView = [subviews objectAtIndex:0]; 
    // Add first constraint 
    [newVerticalConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-10-[firstView]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(firstView)]]; 

    for (int i = 1; i < [subviews count]; i++) { 
     secondView = [subviews objectAtIndex:i]; 
     [newVerticalConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[firstView]-10-[secondView]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(firstView,secondView)]]; 
     firstView = secondView; 
    } 

    // Add last constraint 
    [newVerticalConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[firstView]-10-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(firstView)]]; 

    [superview removeConstraints:self.verticalConstraints]; 
    [superview addConstraints:newVerticalConstraints]; 
    // Save all vertical constraints to be able to remove them 
    self.verticalConstraints = newVerticalConstraints; 
}